The port of Calais was temporarily closed on Saturday after a ferry was stormed by 50 migrants from the nearby "Jungle" camp, earlier visited by Jeremy Corbyn, reports The Telegraph.
Up to 500 migrants had broken off from a protest march through the town about migrants' conditions, according to the mayor, Natacha Bouchart.
Around 150 then broke through the port's perimeter fence, and 50 made it to the gangplanks of the P&O ferry Spirit of Britain. Photographs later showed the migrants standing on the upper decks of the ferry.
A French official said: "A group of 500 people forced their way through police lines and headed to the port, and 150 people were able to get into the fenced-off area. Of these, a group of some 50 managed to board a ferry."
For a few hours the migrants blocked the gangway to the ferry to prevent police getting on board.
Later in a statement, the port of Calais said: "The evacuation is complete, there are no more migrants on the ferry. The evacuation was conducted calmly by police."
Ferry services resumed at 8:30pmm local time, regional officials said.
The incident came after “serious disorder” took place in the centre of Calais, according to the mayor, at the end of a largely peaceful demonstration by about 2,000 activists from the UK and other countries as well as migrants from the nearby ‘Jungle’.
Twice this week there were clashes between riot police in Calais and hundreds of migrants from the Jungle, who mostly come from troubled countries such as Syria, Afghanistan, Sudan or Eritrea.
Police were called to try and remove the migrants, but in the meantime the mayor said the port was closed.
She issued an angry stream of tweets aimed at both the international support groups who organised the march and at the French government.
"This is proof that demonstrations organised by pseudo-defenders of migrants are essentially intended to attack normal life," she said. "I had made clear to the government my disapproval of this demonstration."
Before going to the Jungle, Mr Corbyn had visited another migrant camp in nearby Dunkirk and decried the "dreadful conditions" there for its 2,500 thousand occupants, most of them Kurds from Syria, Iraq and Iran.
The Labour leader's visit came amid growing urgency over the migrant crisis, with French prime minister Manuel Valls warning the huge influx was putting the European Union's future in "grave danger".
Four Syrian migrants arrived in Britain this week from the camp in Calais after a landmark ruling by a UK court which could see more crossing the Channel.
The court cited European Union legislation, under which those who have a relative living legally in another European country - as the four Syrians do in Britain - have a legal entitlement to apply to seek asylum there.
Under the rules, asylum seekers should first claim asylum in France, but the court agreed that bureaucratic failures meant this rarely happened, and that evidence of a written claim to asylum in France was sufficient.
Read more of this report from The Telegraph.
See also: The shameful container camp for the migrants of Calais