British Airways made a new offer to cabin crew on Friday in a bid to end a long-running dispute over pay and conditions before a ballot on further strikes next Tuesday.

The Unite union, which represents 90 percent of BA's 12,000 cabin crew, responded coolly that it was not at all optimistic the new offer provides a basis for resolution of the dispute.

We will of course be considering it and consulting with our cabin crew representatives before making a formal response, said Unite Joint General Secretary Derek Simpson.

BA, which has already lost 150 million pounds ($225 million) this year from a series of strikes, said it was offering cabin crew a new top-up payment that guaranteed existing crew would not lose out on route allowances when new recruits begin flying in the autumn.

BA said the new top-up payment means crew will receive a guaranteed minimum of variable pay, irrespective of the routes they fly.

The airline also withdrew its proposal to fund increased staffing levels on some flights through a reduction in crew allowances.

BA said the new offer included two years of guaranteed rises in basic salary from February 2011 in addition to annual incremental pay increases.

We have changed our offer in line with feedback we have received from crew and we genuinely believe that it can end this dispute, said BA Head of Cabin Crew Bill Francis.

The two sides held a meeting earlier Friday under the watch of Britain's industry mediator Acas.

Acas said in a statement it hoped to reconvene with the parties next week.

Unite plans to start balloting members next Tuesday over possible walkouts beginning on August 3. The union had given BA until the start of the ballot period to demonstrate it was willing to find a solution.

The two sides had made headway on pay and crewing levels, but Unite said it wanted the reinstatement of travel allowances removed from striking crew and the withdrawal of all disciplinary action against its members.

A third sticking point is BA's use of temporary cabin crew and employees from other areas within the company to staff flights during previous strikes.

On Thursday, BA said it planned to recruit over 1,000 new cabin crew on lower wages than current staff.

Shares in BA closed on Friday down 0.3 percent at 207.2 pence.

(Additional reporting by Kylie MacLellan; Editing by Dan Lalor and Will Waterman)

($1=.6680 Pound)