Gordon Brown waded into the fire dispute for the first time yesterday.

Speaking in the Commons, the chancellor made his first public comments on the strike, declaring that it was coming at the "exactly the wrong time, with exactly the wrong claim, pursuing the wrong methods to demand wage rises so much higher than inflation".

Brown told MPs that high wage demands were unacceptable at a time when the world is going through a period of economic uncertainty.

And he insisted that "just as we must have continued discipline on pay in the private sector it is essential that we have continued discipline in the way we approach public sector pay".

After "very constructive" talks with deputy prime minister John Prescott yesterday, the Fire Brigades Union announced that it would hold more meetings with local authority employers later today.

In what is being seen as a positive development, the union will unveil its own 10-point modernisation plan.

A union spokesman said the dispute is now at a "crucial stage" - although many expect Friday's eight-day strike will be called-off.

Interviewed on television last night, Tony Blair said: "One thing has got to be very, very clear - we cannot pay more money out unless it is tied to changes within the fire service."

The prime minister added that if an exception was made for one group of public sector workers, he would then face similar calls from others.

"I don't know what I would say to the nurses, the police officers, the teachers, the doctors who turn and say, 'I'm doing a very difficult job'."

In a boost for the union, the public's backing for the strikes has risen from 47 per cent to 53 per cent over the last month, according to a new ICM poll for the Guardian.