Eurostar passengers bound for the UK faced huge queues in Paris on Wednesday after French border officials worked-to-rule to simulate the effect of a no-deal Brexit on cross-channel services.

The protest by the customs officers at Gare du Nord, who say France is not ready for Brexit, follows a similar action by workers at channel ports that has been taking place since the start of the week.

Trucks were backed up for several miles on roads leading to both Dunkirk and Calais during the action, the AFP news agency said.

Eurostar trains from the French capital were delayed by up to an hour on Wednesday because of the trial checks. Passengers reported that officials were asking more questions than normal at passport control, and security checks on bags were also taking longer than normal.

“Customs officers are strictly applying the rules and reinforcing controls,” David-Olivier Caron, an official from the CFDT trade union, said.

Workers are demanding more staff to help them after Brexit, as well as better overnight pay and a danger allowance ahead of the UK’s departure, which on paper is set to happen on 29 March.

Philippe Bollengier from the CGT union added: “There will be stronger controls. Today you have a demonstration of what is going to happen.”

A spokesperson for Eurostar said: “Eurostar trains departing Paris today are subject to delays of up to 60 minutes.

“This is due to passport and security checks, carried out by French customs officers, taking longer than usual. We are sorry for any inconvenience this may cause our passengers.”

There have been dire predictions about the effect no-deal will have on transport to the UK. The European Commission earlier this year brought forward an emergency policy to keep trains running though the Channel Tunnel after Brexit, amid fears that they could be stopped altogether.

Countries including France and the Netherlands have made significant investments at ports and airports, including hiring more officials, in a bid to pre-empt any difficulties caused by extra customs checks.