Food and water were being distributed to lorry drivers stranded on what could be the hottest day of the year as protesters continued to cripple cross-Channel services.
British Coastguard teams were 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.
The chaos on both sides of the Channel began on Monday when MyFerryLink workers staged a wildcat strike in protest at expected job cuts in the French port city.
Ferry services to and from Dover have been affected, while the Channel Tunnel reopened yesterday afternoon following a three-hour shut down.
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 has implemented Phase 3 of Operation Stack, where freight traffic is held on the coastbound carriageway of the M20.
Dover Coastguard watch officer Tracy Hawke-Treneer said: "We are currently helping Kent Police to distribute food and water.
"As an emergency service we have the capability to respond to major incidents when needed, however this does not impact on our maritime search and rescue response capabilities."
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."