British Airways has won an emergency court injunction to stop a 12-day strike by its cabin crew, bringing relief to around one million travellers whose Christmas holiday plans were threatened by the planned walkout.

The High Court backed BA's claim that the ballot of around 13,000 workers by the Unite labour union was illegal because it included members no longer employed by the airline.

That meant that Unite had to call off the strike.

"We are delighted for our customers that the threat of a Christmas strike has been lifted by the court," British Airways said in a statement after the ruling by Justice Laura Cox.

"It is a decision that will be welcomed by hundreds of thousands of families in the U.K. and around the world," the airline added.

Unite said the decision marked a "disgraceful day for democracy" and added that it will hold a fresh ballot unless the dispute is resolved. But the union cannot hold another vote until after Christmas, with a rescheduled strike unlikely before February.

Festive season travellers are not entirely off the hook, with separate strikes over the coming days by ground staff at Heathrow and Aberdeen airports and by drivers on the Eurostar high speed train to continental Europe still scheduled.

But the BA walkout had the potential to impact the largest number of people, given that it almost certainly would have grounded most of BA's planes at a time the airline normally operates 650 flights and carries 90,000 passengers each day.