Unions, port officials, and the French authorities blamed Brexit on Saturday as thousands of holidaymakers faced long delays trying to reach Europe via the English Channel port of Dover.

UK Foreign Secretary Liz Truss laid the blame on Paris, insisting that "the French authorities have not put enough people on the border."

But the French rejected claims that the gridlock was caused by understaffing.

Border checks and extra paperwork for freight traffic were reintroduced when Britain left the European Union last year, ending free movement for people and goods in the bloc.

"An aftermath of Brexit"

French lawmaker Pierre-Henri Dumont, whose constituency includes the French Channel port of Calais, called the travel chaos "an aftermath of Brexit."

"We have to run more checks than before," he told BBC television, predicting it would happen again.

Port of Dover chief executive, Doug Bannister, initially blamed a lack of French border agency staff for the logjam, which saw some holidaymakers wait for six hours or longer to catch their ferries.

But he conceded there were now "increased transaction times" post-Brexit, adding that the port was ready to handle the demand at peak periods.

The leader of Kent County Council, Roger Gough, estimated that 3,000 lorries were waiting to get to the port on Saturday morning. Kent Police said motorists should still expect "significant delays".

Lucy Moreton, from the ISU union that represents borders, immigration, and customs staff, considered that the tailbacks were a "reasonably predictable" result of Brexit.

Train shuttle services were two hours behind schedule

Passengers have to go through both UK and French border checks at Dover before boarding ferries to northern France.

By 12:45 pm (1145 GMT), the Port of Dover said more than 17,000 passengers had already gone through. 

Port of Dover chief executive, Doug Bannister said that some 8,500 vehicles had left the port on Friday, with about 10,000 expected on Saturday.

Queues for the port snaked through Dover and surrounding roads, stretching kilometers (miles), with lorries backed up at the M20 motorway leading to the town.

A traffic management system was rolled out on the M20 to manage the high volume of lorries backed up toward Dover.

That included closing parts of the motorway to non-freight traffic and diverting cars toward the port and the Eurotunnel by other routes.

Eurotunnel said its train shuttle services for vehicles between nearby Folkestone and Coquelles in northern France were two hours behind schedule.

Traffic jams due to an accident on M20

The prefect of the Hauts-de-France region, Georges-Francois Leclerc, affirmed that France had "done its job" by increasing its border staff in Dover from 120 to 200.

Leclerc blamed the traffic jams on an accident on the M20 on Friday for the late arrival of French border agency staff at their posts in Dover.

But he suggested the port itself had not done enough to handle the increased traffic, which typically jumps from 5,000 to 10,000 vehicles daily during the busy summer.

The prefect told reporters in Lille that all French staff were in position at 9:45 am (0845 GMT) instead of 8:30 am.

"Who would have thought that because the French reinforcements were an hour late that it would derail the whole system?" he added.

Leclerc pointed out that "the world has changed. The UK is now a third country to the EU," which means much more time-consuming checks.