Ferry services have resumed between Calais and Dover after three days of cross-Channel chaos caused by protests.
The disruption began on Monday when MyFerryLink workers staged a wildcat strike in protest at expected job cuts in the French port city.
The blockade at Calais was partially lifted at 6pm this evening, allowing P&O to commence a "limited" service.
But with only one sailing at a time allowed to enter the port, ferry services continue to be affected. The Channel Tunnel reopened yesterday afternoon following a three-hour shut-down.
Food and water were distributed throughout today to stranded lorry drivers by British Coastguard teams, drafted in to bring relief as huge tailbacks caused by striking ferry workers who closed the Port of Calais stacked up on the M20 in Kent.
Port of Dover officials admitted this morning that they had no idea when the industrial action - the second strike by ferry workers in a week - would end.
A Port of Dover spokesman said: "We sincerely regret the impact to the travelling public, freight and the Dover community of a situation that is beyond our control.
"We will continue to monitor the situation closely in liaison with our ferry partners and the Port of Calais in order to resume normal operations as soon as possible."
Kent Police earlier implemented Phase 3 of Operation Stack, where freight traffic is held on the coastbound carriageway of the M20, which remained in place this evening.
The troubles have come amid the migrant crisis in Calais, where more than 3,000 people displaced from countries including Eritrea, Syria and Afghanistan have set up camp.
Migrants have been taking advantage of slow-moving and queueing traffic by trying to board vehicles bound for Britain.
P&O Ferries chief executive Helen Deeble has hit out with fierce criticism towards the British and French governments, as well as Eurotunnel.
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".
Crew members and catering staff on MyFerryLink services announced the 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.
The Road Haulage Association has waded into the debate, saying the action was having a "massive effect" on the UK economy and was placing livelihoods and lives of hauliers at risk.
Its chief executive Richard Burnett said it was "absolute mayhem". He said: "The time for talking around the table has passed.
"The UK and French governments must acknowledge their responsibilities to all Port of Calais users, move in and act. If this means deployment of the armed forces then so be it.
"Let's get this desperate mess sorted out now and talk about a long term solution afterwards. The scale of the current situation has to be seen to be believed.
"The only word to describe what is happening there is absolute mayhem.
"There appears to be very little, if any, security and demonstrators have closed both the Eurostar and LeShuttle tunnels by setting fire to tyres. This is not only causing disruption on a massive scale, it is inevitably putting many lives at risk."
Kent County Council said its staff provided 2,000 bottles of water and 750 snack meals yesterday, and a further 5,000 bottles, plus 200 meals, were expected to have been distributed today to drivers caught up in Operation Stack.
The Maritime Coastguard Agency, Kent Police and Kent Fire and Rescue Service were helping hand out the drinks and food along the closed stretch of the M20.
Motorists were told to avoid the area. Some have vented their frustration about the delays caused by the strike on the other side of the Channel.
On Twitter, one wrote: "This Operation Stack is a disgrace, wasn't even travelling in the direction of France and it's still causing hour delays."
Another tweeted Conservative Dover MP Charlie Elphicke, saying: "For the record, the people of Dover are now stranded, completely cut off in their own town."
Cabinet minister Oliver Letwin has chaired a meeting of the Government's Cobra emergency committee to discuss the situation in Calais, and Prime Minister David Cameron is due to speak by phone with French President Francois Hollande.
Mr Letwin was joined by Home Office minister James Brokenshire, transport minister Robert Goodwill, senior officials from the Foreign Office and Border Force, representatives of Kent Police and the Highways Agency. Diplomats from the UK Embassy in Paris joined the discussions by video link.
Mr Cameron's official spokeswoman said: "There's an ongoing situation at the port, with it remaining closed although Eurotunnel is open. This is part of us making sure that across Government, working with the agencies and in discussions with the French, we are making sure we are doing all we can to get Calais back open."
Mr Cameron spoke to Mr Hollande for about 10 minutes shortly before taking questions from MPs in the House of Commons.
The PM's spokeswoman said that Mr Cameron welcomed the co-operation Britain had received from the French authorities and said that it was important to get the port open again and to ensure that the Channel Tunnel remains open.
Mr Hollande responded that he was determined to resolve the situation and welcomed the fact that the UK and France were working together on the issue.