Goods and passengers from Britain began arriving on French shores Wednesday following a two-day blockade imposed because of a new variant of the coronavirus that had isolated the U.K. and raised fears of food shortages. But officials warned the backlog would take days to work through.

A deal struck the day before that allows truckers and travelers with a negative virus test to cross the Channel into France brought some relief, but many warned the chaos was a precursor to what Britain may face if it doesn’t come to a trade agreement with the European Union before it leaves the bloc’s economic embrace on Dec. 31.

Reporters with The Associated Press (AP) saw a ferry from Britain pulling into the French port of Calais before dawn Wednesday, and rail operator Eurotunnel said trains carrying freight and car passengers were allowed to cross to the continent beneath the English Channel again. But gridlock persisted and tempers flared at England’s port of Dover, where stranded truckers and travelers were desperate to get home for Christmas. Some truck drivers could be seen scuffling with police.

Nations around the world began barring people from Britain over the weekend after Prime Minister Boris Johnson announced that scientists said a new version of the virus whipping around London and England's southeast may be more contagious. The announcement added to anxieties at a time when Europe has been walloped by soaring new virus infections and deaths.

Some European countries relaxed restrictions on Britain on Wednesday, though many remain in place. Still, it was France’s ban on freight that caused the most alarm, since the U.K. relies heavily on its cross-Channel commercial links to the continent for food at this time of year, especially fresh fruit and vegetables.

Fears of food shortages added to an already glum runup to Christmas in Britain, where authorities have scaled back or canceled plans to relax restrictions for the holiday as daily virus infections soar and many hospitals are nearing capacity. Many Britons were already bracing for disruption, if the U.K. and the EU can’t agree on a new trade deal by the time the country leaves the bloc’s tariff-free single market and customs union in just over a week.

French authorities have insisted that the blockade was based on scientific concerns and not politics, but some couldn’t help but note that it may have offered a glimpse of what Britain can expect next year.

Clement Beaune, France’s European affairs minister, told BFM television during a discussion about the Brexit talks that when it comes to trade, "the British side has much more dependence on Europe than the reverse."

People arriving from Britain are required to have a virus test capable of detecting the new variant, according to a late-night agreement reached after 48 hours of frenzied negotiations among French, British and EU authorities.

British Communities Secretary Robert Jenrick said around 4,000 trucks may be waiting in the county of Kent to cross the Channel and urged other truckers not to head there until the backlog is cleared. It will take "a few days" to test all the drivers before they can travel to France, he said.

"Whatever the number is, whether it is 4,000 or more, it is a significant number to work through," Jenrick said.

Soldiers and contact-tracers were being deployed to the area to administer COVID-19 tests. The backlog caused tension and protests in Dover. One truck driver from Poland complained about the lack of toilet facilities or food at the port.

Ben Richtzenhaim, who drove overnight from Scotland in hopes of reaching Europe by car, was stuck in a huge line despite testing negative.

"Looking around, it doesn’t really seem that there’s a lot of progress being made here," he said. "People are still not moving out of the way and the authorities are not doing something either. So it’s a real deadlock."

The Netherlands, Belgium and Bulgaria relaxed travel restrictions on Britain on Wednesday, but dozens of other countries are continuing to bar travelers. Japan announced that it will reinstate an entry ban on most new arrivals from the country.

Eurostar passenger train traffic was also resuming from Britain to the continent, but only for citizens of Europe’s border-free zone, British citizens with EU residency and those with a special reason to come temporarily, such as truckers.