Between 100 and 150 refugees tried to enter the Channel Tunnel overnight to Thursday in a desperate bid to reach England, according to French news agency AFP.
Some of the refugees reportedly blocked one of the exits of the tunnel, causing delays of up to two hours, tunnel operator Eurotunnel said.
Refugees have been trying for weeks to jump aboard trucks waiting to be loaded on trains or directly on the trains themselves, attempting to make it to Great Britain, where they hope for better chances of gaining asylum than in France.
Most of the refugees are fleeing war, dictatorship or poverty in Africa and the Middle East.
Eurotunnel has counted 37,000 escape attempts so this year. The number of actual refugees making the attempts is, however, much lower, as individuals often try several times.
Nine refugees have died on the French side since June while trying to enter the tunnel. The latest fatality came to light on Wednesday morning when the body of a refugee from Sudan was found near the tunnel. Police say the man, aged 25 to 30, was apparently run over by a truck coming off the train he was trying to board.
An estimated 3,000 to 5,000 migrants are said to be waiting in Calais for an opportunity to get to Britain. In view of the escalating situation, Eurotunnel has raised the number of private security guards to around 200. They are being reinforced by some 300 police officers.
Thousands of refugees are waiting for any chance to cross the Channel
British Home Secretary Teresa May has announced that Britain will provide 7 million pounds (9.9 million euros, $10.86 million) in additional funding to improve security at the tunnel on the French side.
Last week, Eurotunnel demanded 9.7 million euros from France and Great Britain to be used for reinforcing security.
Source: dw.com On photo: Migrants walk along railway tracks at Aurotunnel terminal (AFP)