TONY Blair is refusing to back Gordon Brown as his successor, despite the chancellor's demand during a heated meeting last week that he do so.

Advisers close to Blair say he has made up his mind to remain publicly "neutral" between now and his departure from Number 10.

One source close to the prime minister told the Sunday Herald yesterday: "There is no way Tony will be backing Gordon now. That route has been closed down by the events of last week."

Blair's stand will mean an open season of attacks on the chancellor's right to the New Labour throne.

As Blair flew to the Middle East last night for talks with the Israeli prime minister, Ehud Olmert, the probability of peace breaking out inside his party looked slimmer than ever.

Asked during a press conference in Israel whether he would publicly endorse Brown as his successor, Blair refused. He said his previous comments contained "everything any sensible person could ask on that subject."

Even through the most difficult periods of their often acrimonious relationship at the heart of New Labour, Blair has always referred to Brown as holding the potential to be a "good prime minister". When asked, he has routinely acknowledged Brown as his likely successor.

His decision now to claim a neutral position and refuse to say more, will encourage speculation that behind the scenes his silence is encouraging potential challengers to Brown.

More attacks on Brown's suitability as prime minister are expected despite Blair's plea at the Progress think-tank's conference in London yesterday to stop personal criticism and refocus on policy.

The highly personal attacks on Brown were begun by former home secretary Charles Clarke, who called Brown "deluded", "stupid" and a "totally uncollegiate" control freak who could not work with people due to "psychological" issues.

Stephen Byers and Alan Milburn, Blair's so-called loyalist "out-riders" are said to be preparing their own anti-Brown onslaught which could be launched as early as this week.

Asked at the Israeli press conference if he would come to the Chancellor's defence, Blair told the reporter: ''I'm actually surprised you put that question to me since I said so strongly this morning that I wanted an end to this kind of personal attack and I completely condemn any personal attacks of that nature.

"So I hope this should be satisfactory.

I don't want any more people making any more mischief in this situation."

The decision by the prime minister not to back Brown will be seen in such a heated arena as almost a tacit backing for an anyone-but-Brown campaign that is likely to see the home secretary, John Reid, and the education secretary, Alan Johnson, test their ability to defeat the chancellor.

Clarke has not ruled himself out of the fight, and also suggested that Milburn, long out of the Cabinet and regarded as having poorly organised last year's election, had qualities which put him above Brown.

The Northern Ireland secretary, Peter Hain, was one of only a few senior figures to offer Brown his open support yesterday. Hain described Clarke's comments as "quite extraordinary" and claimed they did not reflect his view of the chancellor.

Hain said he expected the leadership handover to come "probably sooner than later". He said he hoped Brown would win.

But others MPs remained distressed that the party was destroying its chances of a fourth term.

Denis McShane, a former Foreign Office minister, said: "New Labour is devouring itself before our very eyes."

Trying to limit the damage, Blair told Progress delegates that there was still three years till the next general election and the party still had time to remake itself. "We can win if we focus on ideas and policy and if we face out and not face in."

He described the events of last week - when he was forced by resignations and threats of further action against Downing Street to announce this would his last year in politics - as "irredeemably old-fashioned".

THE ability of the party to effectively remodel itself for 2007 could only be done, he said, "if we behaved like we did when we were hungry for power before 1997, when we understood that what matters is the people of the country not ourselves."

That advice to whoever will follow him as leader is in stark contrast to his own style of leadership, one he has always said was marked by his ability to take tough decisions that his Cabinet, his party and indeed the electorate were unhappy with.

Wearing a blazer and opennecked shirt, the prime minister looked relaxed and casual, almost as if a great burden had finally been lifted from his shoulders.

But some in audience were less than convinced about Blair's ability to repackage New Labour given his limited time left in office. Roger Lyons, the former head of the MSF union, asked how the reinvention could take place given he only had three months or so left. Blair offered him no answer.