Lorry drivers spoke of their despair at languishing in miles of queues as it emerged that the ongoing strike by ferry workers was costing the UK economy more than £250 million a day.
More than 3,000 truckers were parked on the M20 in Kent for a fourth day as the partial closure of the Port of Calais continued to cripple Channel crossings.
Meanwhile, migrants camped near the French port have been taking advantage of slow-moving and queueing traffic by trying to board UK-bound vehicles.
Kent Police and Port of Dover officials said they had no idea when the industrial action - the second strike by ferry workers in a week - would end.
In the miles of queuing traffic on the M20, veteran lorry driver Graham Davis, from Gloucestershire, said the amount of disruption was getting worse.
He said: "I have been stuck here only since 8am but you could be here for up to 30 hours. It costs thousands, millions, but the French are the French and they just do it.
"Somebody ought to sort it out. We've got to fight all the migrants to get away then we've got strikes and queues, and God knows what.
"It should be made easy but it's not. The worst part is hanging around. It does your head in. I have been doing this for 30 or 40 years and it's just getting worse."
Lithuanian lorry driver Vaidas Petretis, 37, said: "I've only been working for a month and it has been difficult. I have only been stuck for a few hours but many have not moved for maybe a day. It costs a lot of money to just be sat here, but I really don't know what the solution is."
The chaos comes as Home Secretary Theresa May meets her French counterpart Bernard Cazeneuve in Paris and Tim Waggott, chief executive of the Port of Dover, revealed the problems were costing the UK economy £250 million a day.
He said: "The scale and prolonged period of disruption is bad for us all and it is bad for the UK too. The Port handles trade to the value of £100 billion every year and every day that this situation in France continues costs the UK at least £250 million.
"That is simply unacceptable and incredibly damaging."
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 yesterday, 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 badly affected. The Channel Tunnel reopened on Tuesday afternoon following a three-hour shutdown.
There have been calls from the UK's Road Haulage Association for the military to be deployed to break the strike as livelihoods and lives were at risk.
Its chief executive Richard Burnett said it was "absolute mayhem", adding: "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."
Today there were around 3,500 lorries stuck in queues of more than 30 miles on the M20, according to police and highways officials.
It emerged that some foreign truckers have brought their teenage children over with them as school holidays have begun in parts of the Continent.
But Steve Scully, senior resilience officer at Kent County Council, said no welfare problems had been reported among the small number of children stuck in the queues.
Operation Stack was likely to stretch in to the weekend, a spokesman for Highways England said and Chief Superintendent Neil Jerome, of Kent Police, said it could take days for the backlog of traffic to clear after the port fully reopens.
Speaking at Boxley, near Maidstone, he said: "We have been taking this seriously from the start. However, what that does mean is that the volume of lorries entering Stack has exceeded the number of lorries that are then able to cross the Channel.
"My advice to lorry drivers is to think about coming into the county. You will be experiencing a number of hours, if not 24 hours, worth of delays to clear through Stack before you get to Eurotunnel or the Port of Dover."
Mr Jerome was unable to say when the chaos would end, saying: "It's really difficult to say. Clearly we are in the hands of others."
Mr Scully said the humanitarian response involving handing out food and water to stranded drivers had cost around £41,000 but could exceed more than £50,000 if the problems persist beyond the weekend.
Food and water were being distributed throughout to stranded drivers forced to park on the M20.
Kent Police have implemented Phase 4 of Operation Stack, where freight traffic is held on the coastbound carriageway of the M20.
Meanwhile, P&O Ferries chief executive Helen Deeble hit out about the ferry disruptions caused by the strike, with fierce criticism of 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.
A meeting of the Government's Cobra emergency committee was being chaired this evening by Cabinet minister Oliver Letwin to discuss the latest situation in Calais.