A peace deal between British Airways and cabin crew looks unlikely after union representatives refused to back a new offer.

Officials from the British Airlines Stewards and Stewardesses Association (BASSA) joined colleagues in the Amicus union in refusing to recommend the offer to union members.

Both the unions are factions of Unite, which struck the deal with the airline, and their approval is necessary to implement the agreement which could have brought a resolution to the dispute which has been running for 18 months.

BA chief executive Willie Walsh said the deal would need the support of all three union branches, although while BASSA has refused to back the generous deal, officials have agreed to put it to a union vote.

Under the terms of the new deal, staff would be guaranteed a pay rise of 2.9% next year and 3% the year after as well as receive a one-off bonus worth £6,616 to replace a range of allowances given for international travel.

The airline has even offered striking staff an olive branch, promising to return their lost travel perks by 2013 having originally said they would lose them for good.

A BASSA spokesman said: “There are some good parts within BA’s offer, in particular their acceptance of binding independent Acas arbitration, but there are many other clauses which we simply, as a trade union, cannot recommend.”

So far cabin crew have held strikes for 22 days this year, costing the airline about £150 million.