Boeing told two European airlines on Friday their deliveries of 787 Dreamliner jets would be delayed, as investigations into the problems behind the grounded aircraft continue.
Thomson Airways, owned by Britain's TUI Travel told Reuters delivery of its first Dreamliner, originally scheduled for the end of February, had been "moved out of the month" and it had not been given a new delivery date.
Norwegian Air Shuttle, meanwhile, said it had been notified by Boeing that its delivery schedule was at risk because of an investigation by the U.S. National Transportation Safety Board into the aircraft and the extent of the possible delay was not yet known.
Authorities around the world grounded the technologically advanced 787 on January 16 after a battery fire in Boston and a second incident involving a battery on a flight in Japan. The groundings have cost airlines tens of millions of dollars.
Thomson launched an advertising campaign in Britain in April last year for its new fleet of Dreamliners, which it said represented the "future of long-haul travel". It planned to start using the planes in May.
"Boeing is doing everything it can to resolve the situation. We appreciate that there are many customers who are looking forward to flying on the Dreamliner but unfortunately these circumstances are out of our control," Thomson said.
Both airlines said that they were making backup plans, with the Nordic carrier saying that it would lease aircraft if the 787 was not delivered in time for its long-haul service.
Norwegian was scheduled to receive the first of eight Dreamliners in April and the firm has already sold deeply discounted tickets for its first overseas flights as it aims to take on traditional legacy carriers.
Thomson said its contingency plans included using alternative aircraft for its long-haul flights to Mexico and Florida if delivery was delayed beyond the end of March.
A source close to TUI Travel said this would involve the group using aircraft the new orders were supposed to replace.
TUI Travel told Reuters on Thursday it had no plans to cancel its order for 13 Dreamliner jets.
British Airways, owned by International Airlines Group, said it was in discussions with Boeing but that the first of its 787 planes were still scheduled to be delivered in May.
Virgin Atlantic said delivery of its 16 Dreamliners starting in summer 2014 was unchanged.
TUI Travel, Europe's largest tour operator and majority-owned by German travel group TUI AG, said on Thursday summer bookings by Britons were up 9 percent.
(Reporting by Brenda Goh, additional reporting by Gwladys Fouche and Rhys Jones; editing by Kate Holton and Mike Nesbit)