The tunnel, also known as the Chunnel, runs 50 kilometers (31 miles) from a point near Calais, in northern France, to Folkestone, in southeastern England.
On Tuesday night, 1,500 migrants tried to enter the Channel Tunnel, operator Eurotunnel said. It said its teams found a corpse, which French state radio said is the body of a Sudanese migrant.
And overnight Monday, 2,000 migrants tried to enter
the Channel Tunnel through the French terminal near Calais, Eurotunnel said.
Some of those migrants were injured, Eurotunnel France spokeswoman Cecile Carreras said. French authorities and Eurotunnel personnel were able to enter the tunnel and intervene.
Cutting through fences
Calais police Officer Gilles Debove told French state radio that "2,000 migrants didn't arrive just like that."
"We can't possibly imagine it's a wave of 2,000 migrants," Debove said. "Let us be clear: Those are 2,000 intrusions on the site. To compare, about three weeks ago, it was around 500."
Debove said about 1,000 migrants had been waiting around the Eurotunnel site and had repeatedly cut fences.
Eight recent deaths
Calais has long been a gathering place for migrants trying to find a way into the UK. This year alone, Eurotunnel has intercepted 37,000 migrants, the operator said.
And the attempted journey has been deadly.
Last Friday, a 23-year-old Eritrean woman died after being hit by a car as she was trying to cross into the UK, said Gaetan Genel, a spokesman for France's Nord Pas de Calais region.
The woman was the eighth migrant to die since June 1, Genel said.
Since her death, Pas de Calais administrator Fabienne Buccio announced new safety measures involving the Chunnel.
"The authorities will now work with migrants to inform them about the potential dangers they could face on the A16," Genel said, referring to the road leading to the tunnel.
"They need to be aware that they are putting their lives in danger."
Genel said Buccio also asked authorities to continue installing barriers and to add lighting, which would allow drivers to see when migrants try to jump onto their trucks at night.
An international problem
British Home Secretary Theresa May said France and Great Britain agreed to work together "to return migrants, particularly to West Africa, to ensure that people see that making this journey does not lead to them coming to Europe and being able to settle in Europe."
She said both countries have invested heavily in tunnel security.
"In Calais, the French government has already been pushing in for extra resources and extra police resources," May said. "And the UK government will be pushing up to 17 million pounds ($26.5 million) more to ensure the security of the Eurotunnel."
British Prime Minister David Cameron
said such security measures include added fencing. He also acknowledged the massive disruption in traffic because of the flood of migrants.
"I have every sympathy with holiday makers who are finding access to Calais difficult because of the disturbances there," he said Wednesday. "We will do everything that we can to work with the French and bring these things to a conclusion."
But French Interior Minister Bernard Cazeneuve said the problem extends beyond France and Britain.
"If we want to solve this problem in Calais, if we want to prevent the networks of smugglers from driving vulnerable men, women and kids to Calais, we need to work on this problem in its origin," he said.
"We need to work on this from the migrants' countries of origin and follow their path which leads to the European territory."