The Channel Tunnel has reopened after a three-hour shut down caused by striking ferry workers who lit fires on the tracks.
In a day when a mix of striking ferry workers and desperate migrants caused transport chaos to travellers on both sides of the Channel, P&O Ferries chief executive Helen Deeble hit out with with fierce criticism toward the British and French governments, as well as Eurotunnel.
In a statement she said: "And when is the British Government going to stand up to ensure that we can all get to mainland Europe safely and securely? Every day that the disruption lasts costs UK Plc millions of pounds."
She pointed out that P&O Ferries employs thousands of people on both sides of the Channel and "this damaging and dangerous industrial action is now putting those jobs at risk".
She added: "Let me be clear: the buck stops with the French government. They have shown that they can move swiftly to stop any disruption at the tunnel.
"But they have effectively abandoned any attempt to maintain security at the port of Calais, which makes a nonsense of European co-operation.
Ms Deeble also blamed Eurotunnel for putting passengers in the middle of an industrial relations battle by not securing the jobs of workers involved.
Ferry services to and from Dover in Kent have been hit by the strike, which started at the northern French port at 2.20pm yesterday.
A Eurotunnel spokesman said: "Services restarted through the Channel Tunnel at 15.50 this afternoon. Eurotunnel will build up services progressively through this afternoon and this evening."
"We will be intending to get back to normal service as soon possible."
The shut down happened at the blockaded port of Calais about 12.45pm.
It is understood that about 30 to 50 protesters cut their way through fences in to the Eurotunnel site where they blocked the track with burning tyres.
Both Eurostar and Shuttle services were halted. It is the second time in week that services have been hit. The UK Government described the situation as "completely unacceptable".
Crew members and catering staff on MyFerrylink services announced a strike after Eurotunnel, which owns the ships, sold the cross-channel service to rival operator DFDS.
The sale came after a competition authority ruling and left up to 600 jobs, including 70 in Dover, under threat.
Kent Police warned that the port of Calais would be closed until Thursday while Eurotunnel described the situation as "grim", particularly for freight traffic.
Ms Deeble also pointed out that "thousands of holidaymakers and lorry drivers (were) stranded without adequate facilities - even though our employees at the port have done their level best to keep them supplied with food and water".
Of the protesters who have been taken away by the police, Eurotunnel said "we will be pressing charges against them for criminal and civil damage and putting people's live in danger from their actions".
The blockades, which affected all French port to all users, meant the "the local environment is in chaos ... there is gridlock," he said.
In recent days the pattern of migrant activity has spread from attacking trucks on motorways to trying to access the terminal, he noted.
The spokesman said: "There are migrants everywhere which means we have to control the trucks before they get to the site."
With temperatures soaring, police urged travellers to take precautions including keeping their vehicles ventilated to avoid drowsiness and ensuring that babies, children, the elderly and animals are not left alone in stationary cars.
Kent Police, who warned motorists of "significant disruption" to their journeys, said phase two of Operation Stack had been put in place on the M20 southbound.
Non-freight traffic is being diverted on to the A20 from junction eight (Hollingbourne) and rejoining the motorway at junction nine (Ashford West).
This allows backed-up freight traffic to park on the coast-bound carriageway of the M20.
Migrants took advantage of a wildcat strike last week by trying to board UK-bound lorries held up in queues at Calais.
Migrant numbers close to the port have swollen to more than 3,000 since April.
British truckers have reported facing violence and intimidation, and fear being fined if migrants clamber aboard their trucks. Some now take lengthy detours to avoid Calais.