An Eritrean man is understood to have died on the French side of the Channel tunnel as he tried to board a moving freight train bound for the UK.
The unnamed man was found at about 5am near the terminal in Calais, a spokesman for Eurotunnel said.
Aid workers say the situation in the French port has deteriorated in the past few months as more people arrive in the camps, and migrants – many of them unaccompanied children and teenagers – take ever greater risks to get to the UK.
This week, a strike by French workers at the port caused huge tailbacks on motorways leading to both the ferry port and Channel tunnel. Hundreds of migrants – mainly from east Africa, the Middle East and Afghanistan – attempted to take advantage of queuing traffic by breaking into lorries bound for the UK.
On Wednesday, Riswan, a 19-year-old from Pakistan, who had been in the camp, known as the “new jungle”, for a month, told the Guardian the situation was very dangerous.
He said many migrants had been hurt the night before as hundreds of people took ever greater risks to get on to lorries and trains bound for the UK. “One boy was badly injured in his chest when a wheel went over him,” he said. “There was lots of blood.”
Other migrants told how they had tried to cling to the bottom of lorries and trains but had either fallen or been dragged off by police. “Many people have been hurt but what else to do?” said an Afghan man. “We have to keep trying because this is no place to stay.”
Last year, a Guardian investigation revealed that at least 15 people living in the makeshift camps in Calais had died trying to get to the UK in just 12 months. Aid workers say the situation has got even worse in the past six months.
Martine Devries, from Médicins du Monde, a medical charity that works with the migrants, said people in the camp were hungry and living in appalling conditions. “It is much worse than it was before. There are more people and they are becoming more desperate and are taking more risks.
“Last year, people would only make attempts to get on to lorries at night. Now there are so many and they are so desperate people are trying in broad daylight.”
French police do not keep a record of how many migrants die trying to get to the UK from Calais.
On Friday, a spokesman for Eurotunnel said: “I understand that the person was pronounced deceased but we haven’t had any official confirmation of that. We don’t know what the circumstances are just yet, but obviously this is a very regrettable incident.”