Firefighters will not be allow to cripple the economy with inflated pay claims, Tony Blair will vow today.

The Prime Minister is joining the front line in the dispute after his most senior Cabinet colleagues were accused of taking contradictory stances.

Mr Blair will argue that meeting Fire Brigades Union demands would be unfair to other public sector workers, in a Downing Street address to be televised to the nation.

But the union said the press conference at Number 10 - announced last night - showed Mr Blair was "rattled".

Cabinet Minister Peter Hain tried to damp down the heated dispute in a conciliatory interview late last night, saying Mr Blair hoped to create "a very clear understanding that we want the firefighters to achieve a just settlement".

He said: "They deserve justice. Their situation has been ignored for far too long by everybody concerned."

But he was speaking after a fresh jibe at FBU leader Andy Gilchrist from John Prescott, the Cabinet minister responsible for the dispute.

Mr Gilchrist had called for a single, authoritative Government message as he toured picket lines.

Mr Prescott's spokesman said: "Andy Gilchrist has been posturing around braziers but we have not heard anything constructive from him about how to take this forward."

Mr Prescott yesterday signalled support for a deal worth up to 16 per cent over two years.

Within hours Chancellor Gordon Brown dismissed that as "simply not affordable". Deputy Prime Minister Mr Prescott later suggested the deal could be spread over three years instead.

There was also confusion over whether the Treasury would provide transitional funding for a deal until modernisation savings kicked in.

The Chancellor insisted: "There can be no money from reserves. We have made that clear."

However, Mr Prescott has hinted that short-term funding could be available if it was paid for by long-term savings.

It would be "absolutely stupid" not to settle for the sake of a small sum, he said.

The apparent confusion was seized on by unions and the Opposition.

Mr Gilchrist said: "The significant problem now is that we have confusing and, in fact, contradictory messages from very senior parts of the Government.

"It is unclear to firefighters on the ground exactly what the Government position is."

Shadow Chancellor Michael Howard said: "This is a very serious situation. People's lives are at risk but Labour's handling of this has been a shambles."

Last night, the office of the Deputy Prime Minister insisted he had no difference with the Chancellor. "Mr Prescott and Mr Brown are at one on this," said a spokesman.

A FBU spokesman said: "Perhaps Tony Blair can now shed some light on what the Government's strategy is."

The region's Green Goddesses had a fairly quiet night last night. Most of the calls in the first part of the evening were for minor fires, and none endangered life.

Tyne and Wear had the busiest time, receiving 38 calls and responding to 27.

In County Durham, there were 11 calls, all of which were responded to, although one was a hoax.

North Yorkshire had four calls. At one, striking firefighters and RAF servicemen on Green Goddesses worked together to help save the life of a trapped man.

The man was on the ledge of a window in his Scarborough flat when firefighters and servicemen came to the rescue. "This was a potentially life-threatening situation," said an RAF spokesman.