The Port of Dover said that "due to national industrial action in France, services to and from Calais will be suspended from 7am."
P&O Ferries said it has produced an "optimised" sailing schedule in light of the 24-hour strike – known as the National Day of Action in France.
The ferry company also warned "due to the lack of details", it "cannot anticipate the level of disruption" that could still hit its changed sailing schedule.
The Port of Dover said it "is still open with services to Dunkirk running as normal", but travellers should expect it and the local road network around Dover “will be busier than usual".
In a statement, the company added: "Please plan ahead, allowing extra time for your journey and traffic systems that are in place to minimise delays.
"Calais sailings are expected to resume at approximately 2pm UTC from Dover."
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