Chancellor Gordon Brown has weighed into the firefighters' pay row, accusing them of seeking an excessive claim in a time of economic uncertainty.

Mr Brown attacked the timing, size and tactics of the firefighters' demand for a 40% pay rise amid the looming threat of further industrial action on Friday.

We cannot pay more money out unless it is tied to changes within the fire service

Tony Blair

His tough stance contrasted with that of Deputy Prime Minister John Prescott and union officials who described their talks on Monday as "constructive."

Prime Minister Tony Blair reiterated that any pay claim must be linked to reform of the service.

If this week's negotiations fail, the firefighters plan to walk out on Friday for eight days.

'Mixed messages'

Union sources told BBC political correspondent Mark Mardell this industrial action might be delayed if talks between union officials and the government - due to resume on Tuesday - go well.

Mr Brown attacked timing of pay claim

But in the House of Commons, Mr Brown told MPs it was "the wrong time, exactly the wrong claim, pursuing the wrong methods to demand wage rises so much higher than inflation".

Earlier, after meeting Mr Prescott, Fire Brigades Union (FBU) leader Andy Gilchrist said the meeting had been "constructive" but further discussions were needed.

The prime minister's official spokesman said there had still been no agreement on how the FBU would respond to major incidents during strikes.

Meanwhile Mr Blair insisted any pay rise would have to be linked to reform.

"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," he said on ITV1's Tonight with Trevor McDonald.

John McDonnell, Labour MP for Hayes and Harlington, is tabling a Commons early day motion calling on Mr Blair to intervene in the dispute.

But firefighters say it is the deputy prime minister who will take the lead in negotiations.

At the weekend, Mr Prescott visited his local fire station in Hull where firefighters claim he told them he was in charge of cutting a deal.

Firefighter Graeme Lester said: "When pressed about who had the final say in the situation he made it clear that he told Mr Blair to keep his nose out and he would deal with it himself."

Compromise possible

The first 48-hour strike ended on Friday with union leaders hinting a compromise could be reached over their �30,000 pay claim.

The government has denied claims it refused to fund a 16.1% offer over two years last summer.

Employers agree with the government that any pay increase must be linked to modernisation.

Local authority spokesman John Ransford said negotiations would start from the rise - 11% over two years - recommended by the official Bain report.

The government wants the FBU to allow crews of full and part-time firefighters, joint control rooms for fire, ambulance and police services, paramedic training for firefighters and an end to pre-planned overtime.