Willie Walsh, BA chief executive: "We'll do whatever we can to keep BA flying"
The union representing British Airways cabin crew has said its members will go on strike for three days from 20 March and for four days from 27 March.
The Unite union confirmed it would not strike over Easter, but warned there could be further action after 14 April if a resolution had not been agreed.
BA cabin crew are striking over changes to pay and staffing levels imposed by the airline last November.
Another row has broken out between BA and the union about a new offer.
In addition to strike action, the union announced at a press conference that it would also ballot its members on a new offer from BA tabled earlier this week, but said it would not recommend it.
But shortly afterwards, BA boss Willie Walsh told the BBC that the airline's offer was no longer available. He said the offer was conditional on strike action being averted, and so had been withdrawn.
Unite's assistant general secretary Len McCluskey said this latest move by British Airways "beggared belief" and denied that the offer was ever conditional.
Although both sides reasserted that they were available for further talks, the language on both sides has hardened since the strikes were announced.
Instead of travelling in luxury, we're faced with spending a large amount just to get a one-way economy flight, or otherwise losing out on our dream honeymoon and probably most of the money spent on it.
Mr Walsh said the two parties were "not close at all" to coming to an agreement.
The union's proposals to save more than £60m at the loss-making airline included staff pay cuts that BA described as "morally wrong". Mr Walsh said Unite had failed to provide any credible plan to date.
The union contended that it had "made enormous strides and significant offers that meet the demands of BA".
Mr McCluskey said that the withdrawal of the offer showed that the airline's management was "bent on confrontation and never had any intention of an agreement".
The Conservatives accused the government of "looking the other way" because the union was "channelling millions" into "Labour's election coffers".
Prime Minister Gordon Brown urged the two sides to resume negotiations.
"It's in my view essential that the parties continue to talk now even at this 11th hour," he said. "I hope they will do so but I remind them of the danger and risk to the British economy of disruptive strikes going ahead."
BA said all flights to and from London City Airport would be unaffected by strike action, as would all long-haul flights from Gatwick.
Len McCluskey, Unite: "We are unable to recommend BA's offer"
Some short-haul Gatwick flights within the UK and Europe would be cancelled, while some short and long-haul flights to and from Heathrow would also be affected.
BA said it was "very sorry for the stress and disruption Unite's decision will cause".
Consumer group Which? said passengers should be able to get their money back if they are directly affected by the strike, but only once their specific flight has been officially cancelled.
"Passengers whose flights are cancelled should get a full refund, or may be able to rearrange their BA flight date, but that won't compensate for the time and money lost on hotel bookings or tour dates," said Rochelle Turner from Which?.
Questions have been raised about how many of the 7,500 cabin crew that voted for action last month will actually go on strike.
BA has said that those taking part will lose pay and perks, including no longer getting the right to buy heavily-discounted tickets.
The airline has already made extensive contingency plans in preparation for strike action.
It has already trained 1,000 staff to work as cabin crew to cover for any striking workers.
In November, BA reduced the number of cabin crew on long-haul flights and brought in a two-year pay freeze from 2010.
The airline has also proposed new contracts for fresh recruits and newly-promoted staff. These include a single on-board management grade, no seniority, promotion on merit, and pay set at the market rate plus 10%.
However, this would still see new recruits paid significantly less than current staff.
The union said these changes would hit passenger services, as well as the earnings and career prospects of cabin crew.
BA says the cuts are necessary to save money. Last month, it said it lost £342m for the last nine months of 2009. That followed an annual loss of more than £400m reported in May last year.
Unite has acknowledged the "need for change" and has proposed its own cost-cutting package worth £63m through a combination of pay-cuts and part-time working, but this was rejected by BA earlier this week.
The airline said the package would not save as much as Unite claimed, and would involve pay cuts for crew members.
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