Westcountry ferry crossings to France and Spain remain suspended as part of the ongoing dispute at Brittany Ferries.
Talks between unions and the company to break the deadlock continued over the weekend in Roscoff, but without resolution.
Services were halted on Thursday after French crew members took strike action over proposed changes to their working terms and conditions.
Brittany Ferries said despite "constructive" talks, no agreement had yet been reached.
Passengers are being advised to travel to Dover or Calais where "special arrangements" will allow P&O Ferries and MyFerryLink to accept Brittany Ferries tickets.
The only route unaffected by the industrial action is the Poole-Cherbourg passenger service, which is operated by Condor Ferries on behalf of Brittany Ferries.
Passengers have been advised to check Brittany Ferries' website for updates and details.