Brown allies furious as pensions minister resigns from Cabinet

Andrew Smith, the Work and Pensions Secretary, resigned unexpectedly from the Cabinet last night as Tony Blair's plans to reshuffle his ministers ran into trouble.

Mr Smith, a close ally of the Chancellor Gordon Brown, said he wanted to devote more time to his family and Oxford East constituency, but friends said he was unhappy about negative briefings on his performance and he had clashed with Downing Street advisers over plans to reform incapacity benefit.

Last night Nick Brown, another ally of the Chancellor, launched a stinging attack on Mr Blair's style of government and claimed that Mr Smith and other ministers were being "briefed against" at the highest level ahead of a Cabinet reshuffle expected this week.

"There are other ministers that are being briefed against. I think it's a very bad way to proceed," he told Channel 4 News.

Asked if he thought the reshuffle was being well run Mr Brown compared it to the last one which was widely seen as botched. "I think it is as well ordered as last year's," he said.

The former agriculture minister's intervention will be seen by many at Westminster as a sign of open warfare between the Brown and Blair camps.

At a meeting yesterday the Prime Minister tried to persuade Mr Smith to stay, but the Work and Pensions Secretary, who was expected to be moved, decided to pre-empt it.

When Mr Blair was considering a reshuffle in July Mr Smith felt undermined by persistent media reports that he was going to be ousted. Mr Blair is impatient for radical welfare changes and in a speech last week identified incapacity and housing benefit reforms as priorities. Mr Smith is thought to favour an incremental approach.

Downing Street aides insisted that Mr Blair and Mr Smith had a "very amicable" meeting and the outgoing minister did not blame No 10 for the hostile briefings against him.

With the issue of pensions rising up the political agenda, Mr Smith's successor will have a tough job. Among those tipped last night were Patricia Hewitt, the Trade and Industry Secretary; David Miliband, the Schools Standards minister; Ruth Kelly, the Economic Secretary to the Treasury; and Alan Johnson, the Higher Education minister.

Mr Blair will now speed up his reshuffle, which he confirmed today would take place "by the end of the week". This is the second time that a cabinet shake-up has been disrupted by a surprise resignation. When Alan Milburn quit to spend more time with his family last year, Mr Blair was bounced into what became known as his "botched reshuffle". The departure of Mr Smith, a former chief Treasury secretary, is a setback for Mr Brown and comes amid renewed tension between the Prime Minister and Chancellor.

Mr Smith's resignation caught Downing Street by surprise. He told Mr Blair in a letter: "Over the summer, I have discussed with my family the contribution I wish to make in public life. I have chosen to leave the Government and to devote more time to the responsibilities I enjoy in my constituency and to my family."

In his reply, the Prime Minister praised Mr Smith as "an excellent colleague and a first-class minister who will be greatly missed".