The new items found on Reunion Island in the Indian Ocean include pieces of windows, seat cushions and aluminum, Malaysian officials said. But they added that it's unclear whether the objects, which still need to be verified by French authorities, are from MH370.
"The team told us they have managed to collect more debris on the island and we have handed it over to the authorities in France," Malaysian Transport Minister Liow Tiong Lai told reporters. "A plane window and some aluminum foil ... there are many items."
French officials on Reunion and in Paris, however, haven't reported any new plane debris.
And an Australian agency helping coordinate the search for the missing airliner said Wednesday, the day before Malaysia announced the discovery of new items, that there was no indication so far of any more aircraft debris.
"A great deal of additional material has been handed over to the police" on Reunion, Australia's Joint Agency Coordination Centre said in a statement. "While this is being examined, so far none of it appears to have come from an aircraft."
The Australians are in charge of the underwater search for Flight 370 in the eastern Indian Ocean, thousands of miles from Reunion. Malaysia has overall responsibility for the investigation into the loss of the plane.
Although Malaysian Prime Minister Najib Razak announced that the wing part found last week, which is called a flaperon, is certainly from MH370, other officials have expressed more caution and say that more testing is needed.
Less than an hour after the Prime Minister's statement, Paris Deputy Prosecutor Serge Mackowiak used slightly less definitive language. He said that there were "very strong presumptions" that the debris from Reunion is from MH370, but that absolute certainty was not yet possible.
Malaysian officials provided more details later Thursday of what makes them sure it was from the missing jet, including a serial number that matches technical records.
The Boeing 777, carrying 239 people, disappeared on a flight from Kuala Lumpur, Malaysia, to Beijing on March 8, 2014.
Some families of those on board have said they are angry, frustrated and bewildered
by what they've been told.
"I was left somewhat confused and, frankly, a little angry and dismayed," said K.S. Narendran, whose wife was one of the passengers
"I didn't hear facts. I didn't hear the basics. I heard nothing," he said, "and so it leaves me wondering whether there is a foregone conclusion and everyone is racing for the finish."
The families of Chinese passengers, the most numerous nationality on the flight, were also unsatisfied.
"I don't believe this. I don't!" said Xu Jinghong, whose mother was on board Flight 370. "I am furious and I think this announcement is very irresponsible."
Chinese families said last week they wanted "confirmation of 100% certainty" from authorities that the part was from MH370. But the differing Malaysian and French statements appeared to leave them with room for uncertainty.
Other relatives said that the flaperon was only a small piece of a much larger puzzle.
"It's not the end," Jacquita Gonzales, wife of crew member Patrick Gomes, told reporters. "Although they found something, you know, it's not the end. They still need to find the whole plane and our spouses as well. We still want them back."
Lim Khim Fatt's husband was on the flight.
"There's a lot of questions that haven't been answered yet," she said.
A history of family skepticism
Some families have long been skeptical and disappointed by how Malaysian officials have handled looking for and delivering news about the missing plane.
The Malaysian government has been wrong several times
before. On March 17, for example, Malaysian authorities publicly confirmed the final words from the cockpit as "All right, good night."
The innocuous bit of radio banter became yet another headache for investigators when, after days of prodding from reporters and family members, they released a transcript showing the final words were actually, "Good night Malaysian three seven zero."
Malaysian military radar captured signatures of what was believed to have been Flight 370, but it wasn't immediately noticed.
While the radar data was the key reason for expanding the search west of Malaysia, it took officials until March 11 -- three days after the disappearance -- to explain why they were looking so far off the plane's expected course. All the while, search efforts continued in places where data showed it could not have been -- the Gulf of Thailand and the South China Sea.
issued a month after the plane's disappearance also highlighted snafus in crucial communication between air traffic control centers and Malaysia Airlines on the morning Flight 370 disappeared.
Najib, the Malaysian Prime Minister, didn't go into any detail in his statement early Thursday on what Malaysian officials believe provides the conclusive link between the flaperon found on Reunion and MH370.
But Malaysia's Transport Ministry provided more information later in the day, saying that a serial number on the wing part matches Malaysia Airlines' technical records.
The ministry said it found matches for a maintenance seal and paintwork on the flaperon.
Mackowiak, the Paris deputy prosecutor, had stopped short of announcing a definitive link.
Boeing officials have concluded that the part's technical features -- such as its color and the structure of its joints -- confirm that it's from a 777 aircraft, he said.
Drawing on documentation provided by Malaysia Airlines, experts also identified "common technical characteristics" between the flaperon found on Reunion and that of Flight 370, Mackowiak said.
His more cautious language highlights the complex, multinational nature of the investigation into what happened to MH370.
Malaysia Airlines said in a statement that the confirmation announced by Najib, which it described as "a major breakthrough," had been made jointly by French, Malaysian, Chinese and Australian officials.
But a source close to the investigation told CNN that French and U.S. experts examining the flaperon have not yet found anything that would definitively link it to Flight 370. The American officials involved are from the National Transportation Safety Board.
While it is expected that the wing part will eventually be matched to MH370, the source said that there was so far nothing precise enough for 100% confirmation.
The next steps
The analysis of the flaperon will continue at a specialized lab near Toulouse, France.
"The experts are carrying out their work promptly in order to provide complete and reliable information as soon as possible to the victims' families," Mackowiak said.
But he cautioned that he was unable to specify when the results of the ongoing analysis would be announced.
"On a forensic investigation, which is what's going on in France, you don't use the process of elimination and say, well, it must be a flap," said David Soucie, a CNN aviation analyst. "You have to have forensic proof, which is the samples from the paint, from the metal, to tie it specifically to the aircraft. That's what they're waiting for, and that's what they mean by 100% conclusive."
Experts have said that investigators may be able to glean clues from the wing debris about Flight 370's final moments before it is believed to have gone down in the southern Indian Ocean. Did it break apart in midair or hit the water intact?
But neither the French nor the Malaysians made any reference to that aspect of the analysis.
Australian Prime Minister Tony Abbott said Thursday that the Reunion Island discovery "suggests that for the first time we might be a little bit closer to solving this baffling mystery."
The remnants of a suitcase that were found near the flaperon on Reunion are being sent to a different French lab for examination, Mackowiak said.
While a Malaysian official described apparently new plane debris that was found, a journalist on Reunion Island said, citing police, that no debris was reported or handed in Thursday. Police also say that nothing definitive has been turned in during the past week.
Additional air and water resources will be deployed off the coast of the island to look for debris, the French Defense Ministry announced late Thursday. A plane could be flying over the area as early as Friday morning.
French paramilitary operations will also be conducted, including foot patrols, helicopter and naval search missions, authorities said. The statement made no mention of any new plane parts being discovered.
It's anyone's guess whether many items from MH370 are likely to find their way to the remote island or others in the region.
"The problem is the only way for parts of the plane to get to Reunion Island is to continue to float," said Mary Schiavo, a CNN aviation analyst. "The flaperon could because there are spaces inside that part that could allow air to be trapped and for it to float."
But a lot of other potentially buoyant objects -- such as tennis shoes, bits of luggage and items from the plane's galley -- are likely to have become waterlogged and sunk after long months out in the ocean, she said.
The bigger, heavier parts of the aircraft are likely to have gone down into the depths more quickly.
Finding the plane's cockpit voice recorder and flight data recorder, as well as the cockpit itself, is likely to be investigators' best hope of unlocking the mystery of why the plane flew dramatically off course and lost communication with air traffic control.
Martin Dolan, chief commissioner of the Australian Transport Safety Bureau, said authorities have high confidence in the current search area.
"If the aircraft is in that area, which is highly probable, then we will find it," he said.