Brittany Ferries has cancelled all crossings from Portsmouth and Plymouth to France “until further notice” after two days of wildcat strikes.
French crew members have been taking industrial action in a dispute over proposed changes to terms and conditions to cut costs.
Ferry bosses said they had reluctantly decided to tie up the fleet and cancel all crossings “with immediate effect, until further notice”.
A statement said: “This decision has not been taken lightly, but we cannot subject our passengers to the on-going uncertainty caused by wildcat strikes and cancellation of services at short notice.”
The only route unaffected is the Poole-Cherbourg passenger crossing which is operated for Brittany Ferries by Condor Ferries.
Passengers are being diverted to Dover under special arrangements with P&O Ferries and MyFerryLink to accept Brittany Ferries tickets. A full refund will be given for unused Brittany Ferries crossings.
Talks between unions Brittany Ferries and being held in the French port of Roscoff in a bid to end the dispute.
The Brittany Ferries statement added: “Brittany Ferries very much regrets the effect that the disruption will have on our customers but is hopeful that a resolution will be found soon, as discussions with the unions are on-going and will continue throughout the weekend.”