Firefighters were last night preparing for the first national strike in 25 years after an independent review recommended an "insulting" pay offer of 11 per cent over two years.

In a separate dispute, union leaders announced that firefighters, security guards and other workers at seven airports will stage six one-day walkouts over pay.

The Transport and General Workers Union's members at airports will walk out on November 28, December 2, 10, 15 and 23, and January 2.

The airports - Heathrow, Gatwick, Stansted, South-ampton, Aberdeen, Glasgow and Edinburgh - will not be able to operate on strike days, said the union.

The main firefighters dispute took a dramatic turn following the publication of an interim report by a review group chaired by Sir George Bain.

Officials had briefed some sections of the media over the weekend that the review would recommend a "substantial" wage rise in return for big changes to working practices.

But the Fire Brigades Union was left dumbfounded when it emerged that the Bain review was suggesting a rise of four per cent - exactly the same as an offer already rejected- followed by an increase of seven per cent in a year's time. The union is seeking a 40 per cent rise to take salaries to £30,000 and had been boycotting the Bain review because it suspected it would not address its claim seriously.

FBU general secretary Andy Gilchrist said Sir George's intervention had been "disastrous", adding: "He has effectively wrecked the pay talks. We are currently employed on a salvage operation to see if there is any hope of putting things back together again."

Talks between the union and employers will resume today, but the first of a series of strikes, due to start at 6pm tomorrow, now looks certain to go ahead. It will last for 48 hours.

Mr Gilchrist said it was "provocative" to suggest a rise of four per cent, which had already been rejected. "We are beginning to suspect that those in the dark corners of Downing Street are deliberately trying to provoke a strike."

Fire Service Minister Nick Raynsford welcomed the Bain recommendation.

"These proposals hold out the prospect of a significant pay rise in exchange for a significant package of reforms," he said.

Mr Raynsford said the 11 per cent went "way beyond" the level of increase most public sector workers were receiving.

"It holds out the prospect of significant changes to some of the more restrictive practices which have inhibited pay increases."