Members of Unite will walk out for five days, hitting the school half-term holidays, with a further five-day stoppage planned from June 5.

Unite said the 12 days of strikes since last March had now cost BA £84 million with losses of a further £70 million if the next industrial action is not averted.

Talks between the two sides ended without agreement on Friday with Unite accusing BA's chief executive Willie Walsh of blocking a deal.

Derek Simpson, Unite's joint leader, said of Mr Walsh: "He has refused to reinstate travel concessions in full despite Unite making it clear that the union would suspend the strike if he did so.

"It would cost BA nothing to reinstate these travel concessions yet Willie Walsh is prepared to see the strike continue, putting the travel plans of thousands of passengers at risk and costing BA over £100 million over the course of this dispute. Unite have made it absolutely clear that we remain available at any time day or night to meet again with the company."

BA said it plans to run more flights in the coming days than during the previous industrial action claiming that more cabin crew were reporting for duty.

The conciliation service Acas said Friday's talks were adjourned without the parties reaching an agreement adding that officials will be in touch with the two sides to arrange future talks.

Meanwhile, Unite will hold its annual conference in Manchester from Monday with the BA dispute set to dominate the gathering of 700 activists.

BA said it will increase its flying schedule in the coming week as more cabin crew than expected had decided to work as normal during the industrial action.