Migrants seeking to slip into Britain sought to stow away on waiting trucks on the French side of the Channel Tunnel on Wednesday as labor protests by ferry workers brought traffic to a halt.
It was the second time in a week that migrants from Africa and the Middle East had sought to profit from strikes by workers over threatened redundancies at the MyFerryLink company in the northern port of Calais.
They were blocking the port for a third day on Wednesday and a ferry union official said they would seek again to disrupt traffic through the Channel Tunnel for 48 hours from Thursday.
"We will pursue our actions to make the French government budge. From midday Thursday we will carry out actions disrupting the tunnel," said Eric Vercoutre, adding that action was planned to last 48 hours.
Dozens of migrants sat on the roadside around the port in the hope of sneaking aboard one of the vehicles, lined up bumper to bumper to limit their chance of getting in the back doors.
Adam, 36, a Sudanese migrant who fled the war-torn Darfur region, said he had nothing to lose and hoped to take advantage of the chaos.
"I am from the Zaghawa ethnic group and I no longer have a future in Sudan although I have graduated," he said. "I have been in France for the last two months and our life these days is very difficult. I hope to arrive to the U.K. because I will have identification documents quicker than in France."
The latest disruption scheduled for Thursday and Friday will coincide with a traditional surge in travel at the start of school summer holidays. French air traffic controllers are also planning stoppages over a separate set of grievances.
Calais is one of the flashpoint areas of the immigration crisis facing European Union countries, struggling to agree between themselves how to deal with the thousands of migrants heading their way to escape conflict or poverty.
Up to 3,000 migrants are estimated to be amassed around the port. Many want to get to Britain because they speak English, have family connections or are convinced they stand a better chance of getting a job there.
"Some try to get on the lorries by all possible means. Sometimes they cause damage to the freight we carry and then the client may refuse to pay for the freight we ship," said a 58-year-old truck driver who gave his name as Elso.
Workers at ferry service MyFerryLink are trying to prevent job cuts after their company was sold to a Danish firm earlier this month. MyFerryLink was previously owned by Eurotunnel, the company that operates the undersea cross-Channel rail link.