Services through the Channel Tunnel were returning to normal on Wednesday after a day of disruption caused by striking French ferry workers.
The tunnel had to be shut on Tuesday when the workers broke in and migrants attempted to board UK-bound lorries and services were suspended for several hours.
Migrants were seen on Wednesday at the side of the motorway in Calais while others were seen opening the back doors on lorries stuck in traffic.
Eurotunnel said that its passenger and freight shuttles were running as scheduled through the tunnel on Wednesday while high-speed train company Eurostar was operating a full service from London through the tunnel to Paris and Brussels.
The ferry workers’ action closed the port of Calais for a time on Tuesday, but the port was open on Wednesday and Dover-Calais sailings were operating normally.
More resources will be put into screening arrivals at Dover, Britain's immigration minister James Brokenshire has said, adding that extra French police officers are being deployed in Calais to deal with the problem.
The travel problems came amid a worsening migrant situation near the Port of Calais where numbers camped there have swelled to more than 3,000 since April.
Aid workers have reported a "catastrophic" situation, with predictions that some 2,000 more migrants displaced from war-torn countries including Eritrea, Syria and Afghanistan could arrive over the summer.
Mr Brokenshire told the BBC: "It is hugely regrettable that we've seen these incidents occurring as a result of industrial action in France.
“We are putting additional resourcing into the port of Dover to enhance screenings and detections there so that we’re looking at this on both sides of the Channel.”
The deputy mayor of Calais, Philippe Mignonet, reiterated calls from French politicians for the border to be moved from northern France to Britain.
Home secretary Theresa May was given an assurance by her French counterpart that the authorities there "would do the job" in Calais, Mr Brokenshire said.
PA