A man has been arrested after lorry drivers stranded by the French travel ban clashed with police in Kent.
More than 6,000 HGVs are being held in the county, with drivers being tested for Covid-19 before they are allowed into France.
Kent Council leader Roger Gough said the first 20 trucks have now entered the Eurotunnel to make the crossing.
Earlier on Wednesday there were reports of disturbances at Dover and the lorry holding facility in Manston involving those waiting to cross the Channel, Kent Police said.
Footage showed a handful of officers attempting to push back a crowd of protesting drivers in Dover.
One man has been arrested for obstructing a highway in Dover and remains in custody, Kent Police said.
A police car was also damaged during a disturbance at Manston, the force added.
There were 3,750 vehicles at the Manston site as of 6.15pm on Wednesday, along with 632 HGVs on the M20 as part of Operation Stack and 1,690 in Operation Brock, the Department for Transport (DfT) said.
Communities Secretary Robert Jenrick said it may take a “few days” to clear the backlog of lorries waiting to cross into France, despite the travel restrictions being eased.
Kent Council leader Mr Gough said tensions between police and drivers had calmed down but added the situation remained “quite fragile”.
He said 100 lorries have left the Manston site for Dover but had been unable to get to the port as it was being blocked by other vehicles.
“On the M20 side of things, the first 20 HGVs have gone into Eurotunnel,” Mr Gough told Sky News, adding that the number should begin to “pick up” rapidly.
Transport Secretary Grant Shapps said there continued to be “severe delays” despite testing taking place.
He tweeted: “Testing has begun as we look to get traffic moving again between the UK and France.
“However, French border police only acting on agreement from this morning and severe delays continue. Please AVOID Kent while the backlog is cleared. Arriving in the area will delay your journey.”
The UK-French border is reopening. Priority is to get lorries moving & mass testing is underway.— Priti Patel (@pritipatel) December 23, 2020
We urge hauliers not to travel to Kent as we work to alleviate congestion - travelling now will slow things down. Tourist travellers who are not French residents should not travel.
France eased the travel ban on Wednesday, but said those seeking entry into the country from the UK must have a negative coronavirus result.
All truck drivers, regardless of nationality, will be required to take a lateral flow test which can detect the new strain of Covid-19 and return results in about 30 minutes, the Road Haulage Association (RHA) said.
France imposed the travel ban in response to fears about the spread of the more infectious coronavirus strain, which is spreading in the UK.
Hauliers must be able to show proof of a negative test result carried out within the past 72 hours in order to be able to cross into France.
Those who return a positive coronavirus result will be offered a PCR test for a more “refined” result, Mr Jenrick told Sky News.
Drivers will then be moved into Covid-secure hotel accommodation to self-isolate for 10 days if the second test comes back positive.
The disused airfield site at Manston has become the main testing centre for hauliers, with drivers required to self-administer the tests in their cabs under supervision.
Around 170 military personnel, including those from the 36 Engineer Regiment and 1 Irish Guards, are assisting with testing.
Hauliers have been urged not to travel to Kent until further notice.
Dozens of drivers at the Manston site could be seen standing outside their lorries waiting for food and water on Wednesday.
Others were honking their vehicle’s horns in unison to demonstrate their feelings.
Polish lorry driver Greg Baranski, 39, who has been stranded for two days, told the PA news agency: “We have just two food trucks for maybe 2,000 drivers we are waiting for one hamburger for around two hours in the rain. It’s not nice.
“People here are from Romania, Lithuania, Spain, Portugal, and we are all really angry and hungry.”
Lorry drivers at the entrance of the Port of Dover’s Eastern Docks also protested about being stuck at the border.
Drivers standing in small groups shouted “we want to go home” as they tried to shelter from bursts of heavy rain and blustery conditions.
Truck drivers blocked the carriageway out of the Eastern Docks, with one man lying down underneath the front of a lorry before being moved by officers.
Police told hauliers in the afternoon that testing would be getting under way “any minute now” and asked those still blocking the carriageway to return to their vehicles.
An electronic sign which says “return to vehicles, testing to commence” has been put up near the entrance of the Port of Dover’s eastern docks.
The British Retail Consortium (BRC) said there may be shortages of some fresh goods until the backlog is cleared.
“Until the backlog is cleared and supply chains return to normal, we anticipate issues with the availability of some fresh goods,” Andrew Opie, the BRC’s director of food and sustainability, said.
The Associated Press reported seeing a ferry pull into the French port of Calais before dawn on Wednesday, while trains carrying freight and car passengers were allowed to cross under the English Channel.
Channel Tunnel operator Getlink said its freight service takes 35 minutes to travel between the UK and France at 87mph.
It operates a fleet of 18 shuttle trains, with each one capable of carrying up to 32 trucks.