Unions, the Government and local authority employers last night welcomed a decision to call off a second, eight-day strike by firefighters following the surprise intervention of the conciliation service Acas.

Members of the Fire Brigades Union (FBU) had been due to walk out again at 9am tomorrow as part of their long-running campaign to win a 40 per cent pay rise.

But the FBU's executive announced after a four-and-a-half-hour meeting that the latest strike had been suspended for ''exploratory talks''.

The union and the fire authority employers will now make separate submissions to Acas over the next few days in the hope of finding a breakthrough to the deadlocked pay row.

If there is still no agreement, however, the FBU warned that another eight-day strike, due to start on December 16 and run until Christmas Eve, would go ahead as planned.

FBU general secretary Andy Gilchrist welcomed the ''constructive intervention'' of Rita Donaghy, the Acas chairwoman, who contacted both sides in the dispute over the weekend suggesting fresh talks.

Mr Gilchrist said the executive had taken a ''very reasonable and mature'' decision by deciding to suspend the strike.

He denied there had been pressure from rank-and-file firefighters for the next strike to be called off.

Asked whether some people would see the decision as a climbdown by the union he replied: ''That would be a grave mistake. We remain united."

Downing Street welcomed the union's decision but reasserted its position that any extra money for the firefighters must be funded by modernisation.

''If this is a sign they are prepared to negotiate seriously on the whole issue of modernisation, then that is good news,'' the Prime Minister's official spokesman said.

In suspending the strikes, the TUC, which is organising a march and rally in central London in support of the firefighters this weekend, said the FBU had shown ''sound strategic sense".

TUC general secretary John Monks said: ''This is the right move. It puts the pressure on to the employers and Government to come up with an offer that can start real negotiations.''

The development to suspend the walk-out coincides with a report published by the Government yesterday showing how the military had coped during the last eight-day strike.

Ministers said it pointed the way towards many improvements they wanted to see in the fire service, such as sharing control rooms and cutting down on staff at night.

In the North-East, Steve Gregg, the FBU's regional organiser, admitted many firefighters would be relieved that the next strike had been suspended.

But he warned they were ready and willing to return to the picket lines if necessary .