Eurotunnel services have resumed this morning after more than 100 migrants broke into its Calais terminal last night. A "large and co-ordinated" group entered the Channel Tunnel in Calais at around 12.30pm local time (11.30pm BST), Eurotunnel said on its website.
Channel Tunnel staff and two police officers were reportedly injured in the attack. Police arrested around 100 migrants in connection with the incident.
Police entered the tunnel this morning in an attempt to flush the migrants out. A partial service resumed by about 9.15am (8.15am BST) but passengers were being advised to avoid travelling today if possible, a Eurotunnel spokesman said.
"It's a massive invasion and intrusion by a very large and co-ordinated group of migrants," he said. "They are being gathered up by the police authorities."
He added: "It's clearly an organised attack when it comes in such a large number, there are over 100 in this one group. They arrived together and in a well-organised manner broke through the fences and all clearly knew where they were going. There was nobody on trains, there are a small number of passengers affected and customers have gone to the ferry port to continue their journeys."
A total of 13 migrants have died trying to reach Britain since June. An Eritrean man died on Wednesday after being hit by a train near the tunnel entrance in Calais. An estimated 5,000 refugees displaced from countries including Syria, Libya and Eritrea are believed to be camped in and around Calais.
Ministers in both France and Britain in August signed an agreement to set up a new "command and control centre" to tackle smuggling gangs in Calais, as Europe struggles to deal with its biggest refugee crisis since World War II.
The numbers of migrants attempting to cross the Channel Tunnel has spiked over the summer. At its peak, the number of attempts to board lorries or trains was around 2,000 a night, but that has since fallen.
Eurotunnel customers who need to reschedule their booking can visit eurotunnel.comor call 08443 353535. Eurostar services were not affected.