LONDON — Britain agreed on Tuesday night to conduct mass coronavirus tests on truck drivers as part of a deal with France to reopen the border to some travelers and to freight trucks, raising hopes of relief for hundreds of drivers stuck near British ports and for supermarkets warning that they could soon run short of fruit and vegetables.
Two days after France closed its border, fearing a new and possibly more transmissible variant of the coronavirus that has been spreading in Britain, British ministers said rail, air and sea routes between the two countries would be restored on Wednesday morning.
The border closure had left more than 1,500 trucks stranded as the Port of Dover and the Eurotunnel were shut to outbound traffic. Some drivers slept in their trucks for two nights.
More broadly, the supply chain in Europe was disrupted, and industry experts warned that the effects would continue to ripple across the continent for days.
Still, the deal announced Tuesday offered hope to people who had been struggling to get home and to drivers who had been stranded for days. Earlier in the day, France said that select groups of people would be allowed to travel from Britain to France if they could produce proof of a recent negative coronavirus test.
Those now allowed to travel include French and European Union citizens, noncitizens with a permanent residence in the European Union and people whose travel is deemed essential. Among them are diplomats, health workers helping in France’s fight against Covid-19, and the drivers and crew of passenger planes, trains and buses.
The ban on freight trucks was lifted after the French and British governments agreed that drivers could travel to France if they were administered a rapid coronavirus test.
Even with the border closed, trucks from France had been allowed to bring goods into Britain. But few drivers chose to do so, worried they, too, would get marooned on the other side of the border.
It may be some time before a return to normalcy at the ports.
The British government said it would discourage truck drivers from traveling to the congested roads near Dover as it works to ramp up a mass testing program, which may include the military.
“I am pleased that we have made this important progress with our French counterparts this evening,” Grant Shapps, the British government’s transport secretary, said in a statement. “We continue to urge hauliers not to travel to Kent until further notice as we work to alleviate congestion at ports.”
The agreement came hours after the European Union urged member states to step back from the draconian travel bans imposed in recent days. The bloc’s executive urged countries to continue discouraging nonessential travel to and from Britain, but said that British and other European citizens should be allowed to return to their homes and that goods should be allowed to move back and forth.
Many scientists suspect the new variant is already in continental Europe. And they stressed that travel bans were useful only if such measures gave countries time to minimize the spread of the virus within their borders and ramp up efforts to detect the new variant.
“Clearly, we need balance,” Emma Hodcroft, a researcher at the University of Bern in Switzerland, wrote on Twitter. “Act too soon with too little info and you generate panic without evidence — damaging economy, livelihoods and trust. But wait too long, and you could miss a vital window when we have the chance to have the most effective response.”
The discovery of the variant had led in recent days to a lockdown across much of southeastern England and bans on flights and trains between Britain and dozens of countries as they tried to stop the variant from spreading.
Because the trucks passing between France and Britain are continually cycling through Europe, the blockade has disrupted a continentwide freight system that industry experts said could quickly grind to a halt.
Drivers stuck near British ports were given a single cereal bar by local officials on Monday, said Rod McKenzie, the director of policy at the Road Haulage Association, which represents the road transport industry. While drivers pack their own food, he said, they usually do not take much more than they expect to need for their few hours in Britain.
“It’s a story of human misery,” Mr. McKenzie said. “The government planning has been shocking on this, and there are no adequate lavatory facilities on the motorway for the past couple of days with up to 1,000 trucks parked up.”
The British government introduced plans devised for similar problems at the border after the country finalizes its split from the European Union on Dec. 31. It shut off parts of a motorway to allow trucks to park on the road and opened an old airport with room for 4,000 trucks to park.
British commentators noted that the usefulness of Prime Minister Boris Johnson’s Brexit plans for a once-in-a-century pandemic did not do much to raise people’s confidence about how the country would fare if it crashes out of the European Union at month’s end without a deal governing future commercial relations across the English Channel.
Scientists also noted that the new variant’s discovery in Britain did not mean an absence from the rest of Europe. Britain does considerably more genomic sequencing than other countries, allowing it to detect mutations more quickly.
“If you were going to pick it up anywhere, you were going to pick it up in the U.K.,” said Thomas Connor, a professor specializing in pathogen variation at Cardiff University in Wales. “The question for other countries around the world is: What capacity do they have to actually start undertaking some surveillance using genomic sequencing to be able to actually get an idea of what’s circulating there?”
In light of the unlikelihood that the variant is confined to Britain, the European Commission, the bloc’s executive arm, recommended on Tuesday that member states lift blanket bans on travelers from Britain.
It also urged countries not to impose cumbersome and time-consuming requirements for the most thorough coronavirus tests on truck drivers, but rather to rely on more rapid tests while ensuring that any such measures do not disrupt the flow of goods.
“While it is important to take swift temporary precautionary action to limit the further spread of the new strain of the virus and all nonessential travel to and from the U.K. should be discouraged, essential travel and transit of passengers should be facilitated,” the commission said in a statement. “Flight and train bans should be discontinued given the need to ensure essential travel and avoid supply chain disruptions.”
Addressing the issue of European Union citizens stuck in Britain and British people stuck elsewhere on the continent, the commission said they should be exempted from any temporary blockades and allowed to return home.
Those “traveling to their member state or country of residence as well as third-country nationals that enjoy E.U. free movement rights should be exempted from further temporary restrictions provided that they undergo a test or quarantine,” the recommendation said.
Eshe Nelson contributed reporting from London, Matina Stevis-Gridneff from Brussels and Aurelien Breeden from France.