About 2,000 migrants tried to enter the Eurotunnel terminal in the French port town of Calais overnight in a desperate bid to reach England through the Channel tunnel, a spokesman said Tuesday.
"It was the biggest incursion effort in the past month and a half," said the spokesman for Eurotunnel, which is battling often deadly efforts by migrants to smuggle into Britain.
Security at the Calais port was stepped up in mid-June, driving migrants who previously tried to stow away on trucks that take ferries across the Channel to try their luck getting through the tunnel.
The migrants were trying to enter the site "between midnight and 6:00 am," the Eurotunnel spokesman said.
"All our security personnel, that is nearly 200 people, as well as police were called in," he added.
French Interior Minister Bernard Cazeneuve, on a trip to London to discuss the migration issue, confirmed the figures, telling AFP: "There were some arrests and it all passed off without a fuss."
The incident caused serious delays to the Eurotunnel service for much of Tuesday, with passengers held up for around an hour on the British side and 30 minutes on the French side.
A French police source said: "There are regular incursion attempts by small groups that are pushed back but it is not correct to say that there were 2,000 migrants at the same time."
Local authorities were unable to say whether any of the migrants were hurt in the attempt.
Since the beginning of June, eight migrants have died trying to enter the tunnel.
According to the last official count — at the beginning of July — around 3,000 migrants, mainly from Ethiopia, Eritrea, Sudan and Afghanistan, were camped out in Calais trying to get across the Channel.
French Interior Minister Bernard Cazeneuve was in London on Tuesday to hold talks with his counterpart Theresa May on how to tackle the migrant issue, which has been a thorn in the side of Franco-British relations for years.
May said her government would put up an additional seven million pounds (9.8 million euro) to help France secure the Eurotunnel site on its side of the Channel.
"We\’re dealing with terrible criminal gangs," she said.
"We agreed that we will work together to return migrants, particularly to West Africa, to ensure that people see that making this journey does not mean that they are being able to settle in Europe."
The Eurotunnel company itself is seeking 9.7 million euros ($10.67 million) from the British and French governments in compensation for disruption caused by illegal migrants.