Both sides in the British Airways cabin crew dispute were invited today to hold fresh talks to avert a series of strikes due to start next week.

Acas said: "The current dispute has now been running for several months and is not only affecting the parties but also the travelling public at a time when the industry has been hard-hit by the volcanic ash fall-out.

"Acas believe that, given the escalation of this dispute and the widespread impact it will have, it is necessary for us to make this formal public invitation to both sides to attend Acas talks about the issues and to determine what processes may be needed to reach a settlement.

"Acas believe that such discussions must take place urgently and, to that end, will be in touch with both parties to make arrangements about the venue and timing."

BA said it will be responding positively to the invitation, and union sources indicated that Unite would be willing to attend fresh talks, although time is running out to prevent the first stoppages going ahead.

The strikes are due to be held on May 18-22 inclusive, May 24-28, May 30-June 3 and June 5-9, the last day of action coming just two days before the start of the World Cup in South Africa.

The British Airline Pilots Association (Balpa) wrote to Transport Secretary Philip Hammond and Business Secretary Vince Cable today asking them to intervene in the dispute, warning that the planned industrial action would threaten jobs.

Balpa warned that the "unprecedented" strikes will "seriously threaten" BA's ability to maintain job security, as well as terms and conditions of employees.

General secretary Jim McAuslan said: "The last three days have changed the face of British politics, with erstwhile political opponents coming together for the common good. We call on Government to use that political momentum to help solve what are tired 1970s-style industrial relations.

"Without some of that Cameron/Clegg magic, this dispute will put the future of a great airline at risk and disrupt the lives of thousands of British families."

Balpa said ministers should facilitate a meeting between BA boss Willie Walsh and Unite leader Tony Woodley this weekend to try to get next week's strikes suspended.

Meanwhile, BA said staff standing in for union members who took industrial action in March had received a "ringing endorsement" from passengers following a survey which showed satisfaction levels rose in the strike period.

Overall satisfaction was 76% during the month when industrial action was held, 1% up on the previous month.

One respondent was quoted as saying: "My memory is how great the overall experience was from all members of your team, bearing in mind they must have been under enormous pressure."

BA said it intended to operate more than 60% of long-haul and more than 50% of short-haul services from Heathrow during the first five-day walk-out from next Tuesday.

The airline said it planned to fly more than 60,000 customers on each day of the strikes next week, adding that Gatwick and London City airports will not be affected by the industrial action.

Most of its revised short-haul schedule at Heathrow will be operated by BA's own aircraft and cabin crew, supplemented by leasing up to eight aircraft with pilots and cabin crews from five different airlines from the UK and Europe.

The airline has also made arrangements with more than 50 other carriers so it can rebook customers during the strike period on to their flights if they had been due to travel on a cancelled BA service.

Customers can check their bookings on to see if their flight is still operating.

Tony Woodley, joint leader of Unite, said: "The question the BA board should be asking themselves is not how many planes will operate but what is the cost of this strike to the company? BA needs to talk to get this settled."