Thomas Cook pilots will stage three more strikes if talks at the conciliation service Acas do not resolve a pay dispute, their union has announced.

Members of the British Airline Pilots' Association (Balpa) launched a 12-hour walkout at 3am on Friday, although the company said its flights were operating.

The union said there will be three more strikes, on September 23 and 29 and October 3, if there is no breakthrough during talks at Acas starting next week.

Balpa general secretary Brian Strutton said: "I'm pleased that today's strike by Thomas Cook pilots has kick-started negotiations.

"We will now focus on trying to make progress at five days of Acas talks over the next two weeks.

"However, there is still a significant gap between us and Thomas Cook so we cannot assume that those talks will succeed. That's why we've set new strike dates.

"We urge Thomas Cook to come to the Acas table with an acceptable offer so we won't need to use them."

Friday's strike was the first by UK pilots since 1974.

The union said the strike was in protest at year-on-year, real-terms pay cuts, cuts to terms and conditions, and frustration with the company's "intransigent" stance during negotiations.

Balpa said its Thomas Cook members have taken industrial action "extremely reluctantly" and welcomed the news that flights were operating.

Thomas Cook has rescheduled some flights, saying: "Our priority is to make sure all of our customers can still fly on holiday and back home with us during the strike period and we are pleased to confirm that our flights will operate."

A spokesman said: "We have set out a fair pay increase of 1.75% in year one and 2.25% increase in year two, on top of automatic pay increases, in what is a very competitive environment.

"Balpa have not moved from their demands for a pay rise which adds up to more than 10%, or around £10,000 per pilot.

"We hope Balpa come back to the table willing to negotiate.

"We are grateful to our customers for their understanding and to our pilots who are flying today, as well as staff who are working hard to keep the impact of this strike to a minimum.

"All of our flights so far today have operated without disruption."