Cross-channel ferry and holiday company Brittany Ferries is extending the suspension of some services operating between the UK, France and Spain.
It said the move follows continued stringent Covid-19 travel restrictions for passengers on both sides of the channel.
“Only essential travel is currently permitted, and there is little prospect of this easing in the near future,” said the firm.
Four ships that are currently laid up had been due to resume service in late March, but will not now restart services until mid-May at the earliest.
The ships remaining out of service are Barfleur (Poole-Cherbourg), Bretagne (Portsmouth-St Malo), Cap Finistère (Portsmouth-Bilbao and Portsmouth-Santander), and Pont-Aven, which serves Plymouth-Roscoff, Plymouth-Santander and Cork-Roscoff
Ships and routes that are currently operating will continue as scheduled to accommodate essential travel requirements and to enable freight transport.
Brittany Ferries will contact customers who hold bookings on affected sailings to offer alternative travel or a refund.
Christophe Mathieu, Brittany Ferries’ chief executive, said: “Booking levels are extremely low and we are relying on loans to carry us through this difficult period. It is therefore simply not viable to run loss-making routes at this time.
“We are also pushing governments to set out a pragmatic, co-ordinated and clear roadmap to safely re-open travel as soon as the health situation permits.
“We believe that the ramp-up of vaccines means that this re-opening could be considered sooner rather than later.”
About 20% of its annual turnover usually comes from freight traffic, with the rest generated by holidaymakers.