Strike action by port control officials in France is threatening to disrupt thousands of people's Easter holiday plans.
P&O Ferries has warned that talks in Paris have failed, meaning port officials will be going ahead with their strike starting at 8am on Thursday.
The strike, which will last for 24 hours, will likely mean there will be no cross-channel ferries between France and Dover.
Travel operators earlier this week said there has been a huge influx in people booking trips abroad this Easter due to the severe cold weather the UK has been experiencing.
According to the Association of British Travel Agents, around two million Britons are planning to go abroad this Easter.
A statement from the ferry company said: "P&O Ferries regret to advise that following failed pay talks yesterday in Paris, French port control officers will be holding a national day of industrial action commencing at 08.00 tomorrow (Thursday 28 March, 2013) which is likely to affect the majority of ports in France.
"It is as yet unclear as to the kind of action that will be held, which may vary from a 'go-slow' to a temporary or total suspension of services for a 24 hour period.
"Bar a last-minute breakthrough in the negotiations we must assume that there could be disruption to the cross-channel services between Dover and Calais and the other French Channel ports.
"We therefore advise our customers of the potential for long delays between Thursday morning and Saturday morning due to the likely knock-on effect of the disruption and queuing."
It said passengers are being given the option of sailing before the industrial action begins, or to delay their departure until Saturday when there will be spare capacity.
"Anyone who chooses to turn up and wait during the period of the dispute is advised to expect long delays and to prepare accordingly by bringing food and drink," P&O said.