Ferry passengers travelling to the Port of Dover are facing major delays due to increased French security checks.
There are lengthy waits at the port with many people stranded overnight and huge numbers stuck in traffic.
Kent Police said there are delays of between three and five hours on roads into Dover. Motorists have described the traffic as "horrendous".
Checks have now been relaxed and waiting time at the holding area is 40 minutes, the port said.
P&O Ferries said it would hold sailings to ensure customers stuck in queues could travel.
France has been under a state of emergency since last November.
It was brought in after terror attacks in Paris on 13 November left 130 people dead.
The port said French border control booths at Dover had been "seriously understaffed overnight" during an "exceptional security situation".
It said it had raised concerns over French manning levels with the UK Government earlier this week, which had raised the issue with its French counterparts.
Highways England said the A2 is at a "standstill" and is advising people to use the M20/A20.
Kent County Council said it will deliver 11,000 bottles of water to drivers stuck in traffic. Kent Police has advised people to pack food and water.
There are no delays at the Channel Tunnel terminal but people
have been told it will take 90 minutes to check in due to extra security procedures.
No problems have been reported at other major ferry ports.
'Uncomfortable'
Those stuck in the queues have described the situation as "tragic" and said people had been given little information.
Renata Roslak said she and her husband left Birmingham at 19:00 BST on Friday and still had not reached the port.
She said: "It's absolutely horrendous. We have maybe moved half a mile in the last eight hours.
"There isn't even somewhere to turn around and head home.
"I even phoned the police to find out what was happening - we were told that there weren't enough staff to cope with the extra security checks, so ferries are leaving but they aren't full."
Sonia Tutt, 38, on her way to Germany with more than a dozen others in a convoy, said: "Everyone is out of their vehicles, kids are playing
FOOTBALL
."
She added: "There's not been one police car or anything. When we went to join the motorway there was no indication you were likely to be sitting here all night."
'Struggling in heat'
Kris Mazur spent the night on the A20 and said he had moved about one mile in 10 hours.
He said people were standing around at the edge of the road having picnics or sleeping in their cars.
He added: "There has been no access to food or toilets. The motorway is still completely blocked."
Jack Donnelly from London said he had been stuck for more than seven hours.
He said they had not been given much information and families with children were especially struggling with the heat.
'Camping spirit'
"People are helping each other out but the atmosphere is starting to get tense," he added.
Dale Savage was caught in the delays for 12 hours en route to his brother's wedding. He said: "There are a lot of kids here, a lot of young children - a lot of people want to go on their holidays.
"There are no real frustrations, the real problem was no one knew what was going on."
He described a "camping spirit... very much like Glastonbury" but without a band to see at the end of it.
Suzanne Holland said she had finally checked in for the 08:30 crossing - 12 hours after arriving in Dover.
"Anyone would be uncomfortable for that time especially with no information. Had we known we would have tried to sleep," she said.
People have taken to social media to vent their frustrations, including residents caught up in the traffic chaos.
One said on
Twitter: "Late for work. Whole town of Dover is at a standstill. Been sat in my car for 3 hours with no movement."
P&O Ferries said in a
tweet: "Rest assured we'll get you on your way as soon as you pass the checks."
