All Eurostar and LeShuttle services were suspended on Thursday (21 December) after the industrial action was announced. 

Eurostar said: “Due to unexpected strike action by Eurotunnel staff, we’ve had to cancel most services scheduled to run today. 

“Your train is currently scheduled to run, but the situation remains uncertain. So, your journey may be subject to delays. 

“Therefore, we strongly advise you not to travel and recommend that you postpone or cancel your journey.”

Eurostar added: “If you decide to travel, please come to the station at the recommended time stated on your ticket.” 

The rail operator cancelled seven trains between London and Paris on Thursday. 

Eurotunnel said it did not know how long the action would last, but was working to end it as soon as possible.

According to media reports, workers at Getlink – the company that operates the tunnel – have downed tools over salaries, despite rejecting a year-end bonus of €1,000. 

“Today’s call for strike action by representatives of Eurotunnel’s French site staff union has resulted in the complete interruption of service and the closure of our terminals in France and the UK,” the tunnel operator told several media outlets.

The Foreign Office issued an advisory, asking Brits travelling to France, Belgium and the Netherlands to check their operator’s advice before travelling. 

BBC reporter Simon Jones is among the thousands of people stranded at St Pancras.

“An announcement at St Pancras has just informed passengers there will be no Eurostar services before 6.30pm – and all later services – if they run – are fully booked,” he tweeted.