The UK has narrowly avoided a national food shortage after France agreed to let thousands of truck drivers travel between the two countries again.
France issued an immediate travel ban on all people coming from the UK earlier this week, days after health authorities uncovered a mutated strain of coronavirus.
The new strain is 40 to 70 per cent more transmissible than the original virus, the World Health Organisation said.
The second fast-spreading new strain was discovered in South Africa and has since spread to the UK.
Authorities in the UK tightened lockdown rules overnight, with 24 million people ordered to stay at home under Tier 4 lockdown rules. A further 25 million people are in Tier 3 lockdown.
Meanwhile tempers are flaring at the critical English port town of Dover.
Truck drivers complained they were trapped, needing a negative coronavirus test to leave the UK but unable to get one.
Numerous European countries shut their borders to the UK on Sunday amid surging cases and with the new strain spreading quickly.
In England, soldiers were being deployed for a mass-testing programme to deal with the massive traffic jam of trucks.
France today agreed to relax the temporary travel ban, as well as other EU nations, provided anyone wanting to leave the UK can show a negative Covid-19 test no more than 72 hours old.
The travel ban sparked worries the UK could be hit by shortages of some fresh foods just days before Christmas.
"We have worked hard with the British authorities to allow from tomorrow morning ships, trains and also planes to restart safely," Transport Minister Jean-Baptiste Djebbari said.
He said he was "finalising a protocol" to allow the statement to take effect and urged lorry drivers to wait for further announcements.
Despite the breakthrough in talks, congestion around Dover remains unlikely to recede in the short term.
Britain had pushed tests for drivers as part of its solution to the impasse.
More than 2800 trucks are stranded in the southern English county of Kent, unable to make the crossing to France, with drivers having spent a second night sleeping in their cabs.
As night fell on Tuesday, drivers of some 800 trucks parked at a nearby disused airport sounded their horns for more than half an hour in protest.
More than 50 countries banned travel from the UK following the discovery of the strain.
The European Commission earlier urged EU countries to lift travel bans imposed on Britain, where the spread of the new coronavirus variant has spurred global panic just as vaccines are being rolled out worldwide.
The UK is facing one of its biggest health battles in history, as the nation grapples with thousands of cases and a new strain triggering panic across Europe.
The UK's chief scientific adviser Sir Patrick Vallance earlier this week admitted the new strain, which has shown to be more than 60 per cent transmissible than the original strain, had now spread "everywhere" across the country.
"It's more transmissible, we've absolutely got to make sure we've got the right level of restrictions in place," Vallance said.
"I think it is likely that this will grow in numbers of the variant across the country, and I think it's likely therefore that measures are going to need to be increased in some places, not reduced."
Professor Robert West, a health psychologist at the University College London, told the Guardian the nation was facing "economic, human and social disaster".
West called on the UK to reset its coronavirus strategy – something that would likely be costly, but save many lives.
"We need to reset our strategy and move rapidly to a zero [Covid-19] strategy of the kind that many have been proposing," he said.
"It sounds expensive but the alternative could well be a catastrophic collapse in confidence in the country's ability to control the virus and the economic, human and social disaster that would follow."
UK Prime Minister Boris Johnson has been criticised for his management of the coronavirus pandemic.
More than 68,000 UK citizens have lost their lives due to the pandemic, with the nation having one of the highest death tolls in Europe.
British scientists advising the government also observed a higher transmission in children compared with other strains, and are working on this hypothesis to explain its fast spread.