LONDON: British Airways won a High Court battle on Thursday to prevent cabin crew staging a 12-day walkout that would have ruined the travel plans of up to one million people over Christmas and New Year.

Judge Laura Cox granted an injunction to BA, which successfully argued that trade union Unite's staff ballot was invalid because it included workers that had already accepted voluntary redundancy.

BA cabin crew voted overwhelmingly on Monday to strike over job cuts, conditions and pay between December 22 and January 2 in a mass walkout of around 12,500 staff.

However, Judge Cox ruled Thursday that the balance of convenience lay "firmly" with granting BA an injunction to halt the strike.

"A strike of this kind over the twelve days of Christmas is fundamentally more damaging to BA and the wider public than a strike taking place at almost any other time of the year," Judge Cox said.

The industrial action, billed by media as "The Twelve Days of Christmas Strikes," had threatened the holiday plans of BA passengers seeking to visit family and friends over the busy festive break.

The judge also refused Britain's biggest union Unite permission to appeal but added that it could apply to the separate Court of Appeal.

Loss-making British Airways, which is slashing costs in an attempt to return to profitability, reacted with delight to its high-profile victory.

"We are delighted for our customers that the threat of a Christmas strike has been lifted by the court," BA said in a statement.

"It is a decision that will be welcomed by hundreds of thousands of families in the UK and around the world.

"There was never any need for a strike and we hope that Unite will take this opportunity to reflect before deciding its next steps. We believe the public would want that too."

Unite was protesting at BA's imposed contractual changes that include fewer cabin crew on flights, a pay freeze and different working conditions for new members of staff.

The union expressed deep disappointment at the ruling and warned that there would "inevitably" be another ballot for more action if the company did not resolve the row through negotiation.

"While we have never wanted this dispute, it is a disgraceful day for democracy when a court can overrule such an overwhelming decision by employees taken in a secret ballot," said Unite joint general secretaries, Derek Simpson and Tony Woodley, in a statement.

Aviation analysts estimated that the strike could have cost BA between 10 and 30 million pounds (11-33 million euros, 16-49 million dollars) per day.

"We will of course be studying the judgment but the fact remains that this dispute is not settled. Passing the buck to the courts to do management's job for them was never going to be the answer," Simpson and Woodley said.

"BA must accept that there can be no resolution except through negotiation, failing which there will inevitably be a further ballot for industrial action."

Earlier Thursday, BA executives and union bosses had held unsuccessful last-ditch talks in a separate bid to stop the strike.

Prime Minister Gordon Brown had urged both sides on Wednesday to resolve the dispute, saying he was "very worried" about the strike.

The strike threat came at a critical point for BA, which is cutting costs and attempting to merge with Spanish carrier Iberia as part of a bid to remain competitive against its rivals.

BA revealed last month that net losses quadrupled to 217 million pounds in the group's first half, or six months to September.

The airline has announced it will cut an extra 1,200 jobs -- taking the total planned reduction to 4,900 by 2010.

"In recent days, we believe Unite has formed a better understanding of our position and of the ways in which we could move forward," BA said in the statement issued after the court ruling.

"It has also become very clear that our customers do not believe that old-style trade union militancy is relevant to our efforts to move British Airways back toward profitability."