Yulia Skripal poses for the media during an interview in n London, Wednesday May 23, 2018. Yulia Skripal says recovery has been slow and painful, in first interview since nerve agent poisoning. (Dylan Martinez/Pool via AP)
PHOTO: Dylan Martinez/AP
Yulia Skripal poses for the media during an interview in n London, Wednesday May 23, 2018. Yulia Skripal says recovery has been slow and painful, in first interview since nerve agent poisoning. (Dylan Martinez/Pool via AP)
Now playing
02:34
Daughter of poisoned ex-spy: Lucky to be alive
(L/R): Head of Dutch Military Intelligence and Security Service Onno Eichelsheim, Minister of Defence Ank Bijleveld and British ambassador Peter Wilson attend a press conference of the Dutch Military Intelligence and Security Service (MIVD) at The Hague, The Netherlands, on October 4, 2018. - Dutch intelligence thwarted a Russian cyber attack targeting the global chemical weapons watchdog in April and expelled four Russian agents, the government said. The Russians set up a car full of electronic equipment in the car park of a hotel next to the Organisation for the Prohibition for Chemical Weapons in The Hague in a bid to hack its computer system, it said. (Photo by Bart Maat / ANP / AFP) / Netherlands OUT        (Photo credit should read BART MAAT/AFP/Getty Images)
PHOTO: BART MAAT/AFP/Getty Images
(L/R): Head of Dutch Military Intelligence and Security Service Onno Eichelsheim, Minister of Defence Ank Bijleveld and British ambassador Peter Wilson attend a press conference of the Dutch Military Intelligence and Security Service (MIVD) at The Hague, The Netherlands, on October 4, 2018. - Dutch intelligence thwarted a Russian cyber attack targeting the global chemical weapons watchdog in April and expelled four Russian agents, the government said. The Russians set up a car full of electronic equipment in the car park of a hotel next to the Organisation for the Prohibition for Chemical Weapons in The Hague in a bid to hack its computer system, it said. (Photo by Bart Maat / ANP / AFP) / Netherlands OUT (Photo credit should read BART MAAT/AFP/Getty Images)
Now playing
01:11
Russia denies western accusations of attacks
putin response russian spy lon orig bks_00003009.jpg
PHOTO: BBC
putin response russian spy lon orig bks_00003009.jpg
Now playing
01:30
Reporter confronts Putin about spy poisoning
The UK will expel 23 Russian diplomats from the country after concluding that the Russian state is responsible for the attempted murder of former Russian agent, Sergei Skripal and his daughter Yulia in Salisbury on March 4th.  They will have one week to leave.   "For those who seek to do us harm, my message is simple. You are not welcome here."
PHOTO: Bowtie TV
The UK will expel 23 Russian diplomats from the country after concluding that the Russian state is responsible for the attempted murder of former Russian agent, Sergei Skripal and his daughter Yulia in Salisbury on March 4th. They will have one week to leave. "For those who seek to do us harm, my message is simple. You are not welcome here."
Now playing
01:08
Theresa May: UK will expel 23 Russian diplomats
A Russian flag flies next to the US embassy building in Moscow on July 31, 2017. (MLADEN ANTONOV/AFP/Getty Images)
PHOTO: MLADEN ANTONOV/AFP/Getty Images
A Russian flag flies next to the US embassy building in Moscow on July 31, 2017. (MLADEN ANTONOV/AFP/Getty Images)
Now playing
01:04
Suspected Russian spy worked inside US embassy
 Steven Seagal (R) delivers a press conference with Costa Rican President, Oscar Arias (out of frame), on February 11, 2009, at the presidential residence in San Jose. Seagal and Arias met to talk about the possibility of real estate and film industry investments in Costa Rica. AFP PHOTO/ Mayela LOPEZ (Photo credit should read MAYELA LOPEZ/AFP/Getty Images)
PHOTO: MAYELA LOPEZ/AFP/Getty Images
Steven Seagal (R) delivers a press conference with Costa Rican President, Oscar Arias (out of frame), on February 11, 2009, at the presidential residence in San Jose. Seagal and Arias met to talk about the possibility of real estate and film industry investments in Costa Rica. AFP PHOTO/ Mayela LOPEZ (Photo credit should read MAYELA LOPEZ/AFP/Getty Images)
Now playing
02:30
Putin appoints Steven Seagal for diplomat job
russia new nuclear weapons putin chance lkl vpx _00002715.jpg
PHOTO: Russian Defense Ministry
russia new nuclear weapons putin chance lkl vpx _00002715.jpg
Now playing
01:09
Russia releases video of new nuclear weapons
SALISBURY, ENGLAND - JULY 05:  A police officer stands by a cordon in place at Queen Elizabeth Gardens in Salisbury after a major incident was declared when a man and woman were exposed to the Novichok nerve agent on July 5, 2018 in Salisbury, England. The couple, named locally as Dawn Sturgess 44, and Charlie Rowley, 45 were taken to Salisbury District Hospital on Saturday and remain there in a critical condition. In March Russian former spy Sergei Skripal and his 33-year-old daughter Yulia were poisoned with the Russian-made Novichok in the town of Salisbury. British Prime Minister Theresa May has accused Russia of being behind the attack on the former spy and his daughter, expelling 23 Russian diplomats in retaliation. (Photo by Jack Taylor/Getty Images)
PHOTO: Jack Taylor/Getty Images
SALISBURY, ENGLAND - JULY 05: A police officer stands by a cordon in place at Queen Elizabeth Gardens in Salisbury after a major incident was declared when a man and woman were exposed to the Novichok nerve agent on July 5, 2018 in Salisbury, England. The couple, named locally as Dawn Sturgess 44, and Charlie Rowley, 45 were taken to Salisbury District Hospital on Saturday and remain there in a critical condition. In March Russian former spy Sergei Skripal and his 33-year-old daughter Yulia were poisoned with the Russian-made Novichok in the town of Salisbury. British Prime Minister Theresa May has accused Russia of being behind the attack on the former spy and his daughter, expelling 23 Russian diplomats in retaliation. (Photo by Jack Taylor/Getty Images)
Now playing
02:02
Russia denies involvement in poisoning attacks
PHOTO: Reuters
Now playing
00:54
May: Nerve agent poisoning deeply disturbing
 A CNN team accessed the Malaysia Airlines flight 17 (MH17) crash site, July 30, 2014 and found evidence that there are still belongings at the site, including pieces of the plane .
PHOTO: Raja Razek/CNN
A CNN team accessed the Malaysia Airlines flight 17 (MH17) crash site, July 30, 2014 and found evidence that there are still belongings at the site, including pieces of the plane .
Now playing
00:49
Investigators: MH17 downed by Russian missile
PHOTO: GOOGLE EARTH
Now playing
01:28
Russia blames Israel for strikes on Syria
PHOTO: CNN PHOTO ILLUSTRATION/GETTY IMAGES
Now playing
02:36
Why Hungary is looking more and more like Russia
A Russian flag flies next to the US embassy building in Moscow on March 27, 2018. (MLADEN ANTONOV/AFP/Getty Images)
PHOTO: MLADEN ANTONOV/AFP/Getty Images
A Russian flag flies next to the US embassy building in Moscow on March 27, 2018. (MLADEN ANTONOV/AFP/Getty Images)
Now playing
02:26
Russia retaliates, expels 60 US diplomats
Presidential candidate, President Vladimir Putin addresses the crowd during a rally and a concert celebrating the fourth anniversary of Russia's annexation of Crimea at Manezhnaya Square in Moscow on March 18, 2018. / AFP PHOTO / POOL / Alexander Zemlianichenko        (Photo credit should read ALEXANDER ZEMLIANICHENKO/AFP/Getty Images)
PHOTO: ALEXANDER ZEMLIANICHENKO/AFP/AFP/Getty Images
Presidential candidate, President Vladimir Putin addresses the crowd during a rally and a concert celebrating the fourth anniversary of Russia's annexation of Crimea at Manezhnaya Square in Moscow on March 18, 2018. / AFP PHOTO / POOL / Alexander Zemlianichenko (Photo credit should read ALEXANDER ZEMLIANICHENKO/AFP/Getty Images)
Now playing
01:35
Russia votes: How the day unfolded
Russian President Vladimir Putin delivers a speech during a meeting with Russian athletes and team members, who will take part in the upcoming 2018 Pyeongchang Winter Olympic Games, at the Novo-Ogaryovo state residence outside Moscow on January 31, 2018. / AFP PHOTO / SPUTNIK / Alexey NIKOLSKYALEXEY NIKOLSKY/AFP/Getty Images
PHOTO: ALEXEY NIKOLSKY/AFP/AFP/Getty Images
Russian President Vladimir Putin delivers a speech during a meeting with Russian athletes and team members, who will take part in the upcoming 2018 Pyeongchang Winter Olympic Games, at the Novo-Ogaryovo state residence outside Moscow on January 31, 2018. / AFP PHOTO / SPUTNIK / Alexey NIKOLSKYALEXEY NIKOLSKY/AFP/Getty Images
Now playing
03:47
How do you become president of Russia?
(CNN) —  

Police have identified two suspects in the poisoning of former Russian double agent Sergei Skripal and his daughter Yulia, a source with knowledge of the investigation told CNN on Thursday.

The pair left the UK in the wake of the attack on what is believed to have been a commercial flight, the source added.

Their departure was revealed in a coded Russian message to Moscow sent after the attack, which was intercepted by a British base in Cyprus, the source said. The British government blames the Skripals’ poisoning on Russia.

The suspects were identified by UK police, who have been combing through months of surveillance camera footage from UK airports and from Salisbury, the town where the Skripals were poisoned on March 4.

Using facial recognition technology, authorities discovered two “fresh identities” – individuals not known to have been spies or used in other attacks – the source added.

Investigators cross-checked that information with the manifest of the flight on which the suspects were believed to have left Britain. They traveled under aliases, the source said. It is not clear whether the pair are Russian.

An Aeroflot flight at Heathrow airport in London was searched on March 30, an action the British government described at the time as “routine.”

Former Russian spy Sergei Skripal and his daughter, Yulia Skripal, at a restaurant in Salisbury, UK.
PHOTO: Family photo/Pixel 8000 Ltd
Former Russian spy Sergei Skripal and his daughter, Yulia Skripal, at a restaurant in Salisbury, UK.

Escalating tensions following Novichok death

Russia’s Ambassador to the United Kingdom Alexander Yakovenko shrugged off the claims at a Russian Foreign Ministry event in Moscow. “These are the reports of the media,” he told reporters.

“Unfortunately, we don’t have official statements from the British side. I want to hear from Scotland Yard or the Foreign Office. A lot of versions have been appearing in the newspapers. They are not supported by the statements of the Foreign Office,” he said.

The British Foreign Office referred CNN to the police. London’s Metropolitan Police, which is leading the investigation into the Skripals, declined to comment.

Britain’s Press Association news agency also reported Thursday that police had identified suspects in the case. Ben Wallace, a security minister in the British government, described the reports as “ill-informed and wild speculation.”

The news came 10 days after police launched a murder investigation into the death of a British woman who fell ill after being exposed to the same nerve agent used to poison the Skripals. The substance, called Novichok, is a rare Soviet-era military-grade nerve agent.

Dawn Sturgess, 44, and her partner Charlie Rowley, 45, both residents of Amesbury, a town eight miles north of Salisbury, were hospitalized on June 30. Rowley remains in hospital.

Police said the couple had been exposed to Novichok after touching a contaminated item, but said there was no suggestion the couple had been deliberately targeted.

Last week, police said that they had identified a small bottle found in Rowley’s home as the source of the nerve agent that killed his partner.

It is unclear where Rowley found the bottle, or whether it is the same batch of nerve agent that poisoned the Skripals. The Novichok was believed to have been in a perfume bottle, which Sturgess dabbed on her skin thinking it was perfume, three sources briefed on the UK poisoning investigation told CNN on Thursday. That was the reason she got the fatal dose, investigators say.

An inquest into Sturgess’ death was opened Thursday morning and later adjourned until January.

Dawn Sturgess, 44, died after being exposed to Novichok.
PHOTO: Facebook
Dawn Sturgess, 44, died after being exposed to Novichok.

’Highly likely’ Russia was responsible

The attack on the Skripals led to a spiraling diplomatic dispute with Russia. The UK expelled 23 Russian diplomats and more than 20 other countries, including the United States, followed suit.

In a letter to NATO secretary general Jens Stoltenberg in April, UK national security adviser Mark Sedwill said that Russia was “highly likely” responsible for the attack and that there was “no plausible alternative explanation.”

Russia has repeatedly denied any involvement in the attack and has put forward multiple theories as to who may have been behind it.

The Skripals were found unconscious on a bench in the city of Salisbury on March 4. They were treated for exposure to the military-grade nerve agent and discharged separately from hospital several weeks later. Police believe they came into contact with the substance via the door handle of Sergei Skripal’s house.

In April, the Organisation for the Prohibition of Chemical Weapons (OPCW) confirmed the UK’s finding that Novichok was used in the attack. Last week, the watchdog was asked by the UK to deploy another team to determine the nature of the substance to which Sturgess and Rowley were exposed.

The team completed its work Wednesday and will submit the samples for analysis, according to the OPCW.

The Skripal case has drawn comparisons to the poisoning of former Russian spy Alexander Litvinenko, who died a slow death after drinking tea laced with highly radioactive polonium-210 in a Mayfair hotel of London in 2006.

A detailed UK inquiry later concluded that Russian President Vladimir Putin probably approved the operation by Russian agents to kill Litvinenko. The Russian Foreign Ministry dismissed the UK investigation as politically motivated.