Striking French ferry workers at Calais have threatened to continue their action after forcing the closure of the Channel Tunnel.
Trade unionist Eric Vercoutre of MyFerryLink - whose workers are protesting against a buyout by rival DFDS - said more action was planned for 1 July after chaotic scenes on 30 June saw the train link between Britain and Europe shut down for several hours.
"We want to make the French, British and Belgian governments understand that if a solution isn't found to save our 600 jobs, there will be a lot of disruption this summer," Vercoutre told Reuters. "When the mobilisation ramps up, we'll block everything, which could disrupt Eurotunnel."
Eurotunnel said on its website: "Our passenger service is temporarily suspended due to a breach of our terminal boundaries.
"The closure of the Eurotunnel is due to industrial action by MyFerryLink workers from the port of Calais, breaking through the security fences and setting fires on the tracks.
"We strongly advise passengers whose journeys are impacted not to come to our stations, but instead to exchange their ticket online through Eurostar.com.
"We are sorry for the inconvenience to all passengers, and advise them to check Eurostar.com for further updates on when Eurotunnel will reopen and Eurostar services can resume."
British police implemented Operation Stack, where lorries use part of the M20 to Dover and Folkstone to queue for Channel ferry crossings. This caused major traffic jams in the south of England.
At Calais, retired London Stanley Shakespeare and his wife were caught in the chaos as they tried to make their way home from a holiday in Spain.
"This is not a very nice thing to happen to us," Shakespeare told Reuters. "We love France and we love the French people, who are very nice, but as we got here today I may change my mind."