An additional 800 military personnel have been deployed to Kent to help thousands of lorry drivers waiting to cross into France.
In total, about 1,100 troops have been sent to help with the severe disruption caused at the English Channel border, providing coronavirus testing and distributing food and water as part of the operation.
Transport Secretary Grant Shapps has confirmed more than 4,500 lorries have managed to cross the Channel.
But despite efforts to clear the backlog, thousands of hauliers are spending Christmas Day in their cabs.
One lorry driver told Sky News he had been waiting at the airport for two days and was hoping to get back after testing negative for coronavirus.
He said that a train providing food was "empty" with no water and the airport was "full".
Another driver, called Michael, had been waiting in the UK for five days. He said the situation was "no good".
Lorry drivers are now required to show proof of having a negative coronavirus test within the last 72 hours before they are able to cross the English Channel.
Testing is taking place at Manston Airport, a closed section of the M20, and in Dover.
Mr Shapps said that over 10,000 coronavirus tests have been conducted, out of which only 24 have been positive.
He tweeted: "A huge thank you for the tireless efforts of our troops, police, civilian testers, council planners & port & ferry workers for giving up their Xmas to get people home."
Traffic flowed smoothly through Dover on Friday, with French firefighters being drafted in to help with the testing process.
A Port of Dover spokesman said ferry services ran throughout Christmas Eve and will continue on Christmas Day to help ease congestion.
He tweeted: "Some of the German lorry drivers we've been in touch with are on their way home or at home already. Others sadly remain stuck.
"I sincerely hope things will start moving for them soon. This is a difficult Christmas. Our thoughts are with them."
Food deliveries to drivers stuck in Operation Brock on the M20 have been organised by Southeastern railway and Network Rail and delivered by the Salvation Army, with seven trains carrying food departing from London in the past two days.
HM Coastguard said its teams in the Dover area had so far delivered 3,000 hot meals, 600 pizzas, 2,985 packed lunches and 17 pallets of water to those waiting.
The government said catering vans would provide hot food and drinks to hauliers stranded at Manston, with Kent County Council and volunteer groups providing refreshments to those stuck on the M20.
There are more than 250 toilets at Manston, with a further 32 portable toilets added to existing facilities on the M20.