Cross-channel travellers are being warned to expect further disruption next week following the collapse of a loading bay at Calais last month.
No ferries left the port of Dover during the 24-hour French strike
The collapse left the port with only two berths big enough for large cross-channel ferries, one of which will be closed for repairs from Monday.
P&O said its services from Dover would be subject to more delays and cancellations on Monday and Tuesday.
SeaFrance said 10 of its 15 scheduled crossings would be unaffected.
Its other services may be subject to some delays.
It comes after French strike action caused two days of ferry disruption.
No P&O or SeaFrance ferries were able to leave Dover from Wednesday afternoon until Thursday evening due to the 24-hour French national strike.
The ferry service between Dover and Calais has been badly disrupted since the loading bay collapse in early February.
There are regular delays of between two and four hours for passengers heading to Calais and lorry traffic through the port has been badly affected.
P&O said the disruption had cost the company millions and it would be seeking compensation from the Port of Calais.
William Gibbons, head of the Passenger Shipping Association, said the hold-ups were not good news for the industry.
"All our customers have been inconvenienced," he said.
"Luckily it has happened at a time of year when passenger traffic is relatively low.
"We do see it as a temporary problem which will be resolved shortly."
Hoverspeed's catamaran crossing, which resumes on Wednesday after the winter break, uses a different terminal so should be unaffected.