GORDON BROWN declared war on Frank Field yesterday when he sent a key Cabinet ally to accuse the rebel MP of trying to bring him down over the 10p tax row.

In extraordinary comments to journalists, Children’s Secretary Ed Balls suggested the Birkenhead MP was interested in “settling old scores”, rather than in reaching a deal on compensation.

Reacting to Mr Field’s call for the Prime Minister to consider resigning, Mr Balls said talks had been held because Mr Brown “thought his intentions were honourable”, making clear he no longer thought that.

Mr Balls said: “I think it’s very unlikely, on the basis of what I’ve seen, that Frank Field will support any proposals brought forward by the government on the 10p tax.”

And asked if he believed the MP wanted to “bring down the government”, he said: “I will leave you to draw your own conclusions.”

The comments dramatically raised the stakes in the continuing 10p tax row, which could still trigger a big Commons revolt next month, putting Mr Brown’s position in fresh peril.

And it came as No.10 was left reeling from further attacks in the memoirs of Cherie Blair, John Prescott and Lord Levy, Tony Blair’s former chief fundraiser.

Most notably, Ms Blair’s book suggests Mr Brown leaked the 1999 news that she was pregnant with her fourth child – an accusation Mr Brown’s aides said left them “totally baffled”.

In an interview yesterday, Mr Field described Mr Brown’s career as “tragic” and predicted he would be replaced as Labour leader before the next election. The MP said that Mr Brown was prone to “tempers of an indescribable nature” and urged him to take advice from the “people you most love” about quitting.

The Birkenhead MP also vowed to lead a fresh revolt over the abolition of the 10p tax rate when the Finance Bill returned to the Commons, unless Mr Brown finalised a compensation deal.

He said: “There are enough members on the Labour backbenches who will, with others, block the Budget going through. That will make his position intolerable.”

The comments – the first time a Labour MP has suggested Mr Brown is doomed – prompted a furious reaction from Mr Balls, long seen as the Prime Minister’s closest confidante.

Asked about Mr Field, Mr Balls said: “People could look at what he was saying a few weeks ago and believe, at that time, his intentions were honourable.” And he added: “When it becomes about political attacks, or settling old scores, or things which directly damage the government of the day, people think that is not what you should be about.”

Earlier, Health Secretary Alan Johnson also turned his fire on Mr Field and other outspoken critics of Mr Brown, saying: “I think people are tired of this character assassination.”

Last month, Mr Field forced the Prime Minister into a humiliating U-turn over the scrapping of the 10p tax rate, when he won a pledge of compensation.

But he now suspects Mr Brown is trying to wriggle out of that deal, after he suggested some of the 5.3m losers had already been compensated in this year’s Budget.

Conservative leader David Cameron said members of the government increasingly resembled characters “in a soap opera, where they are more concerned with settling scores with each other than with running the country”.