Brown ready for showdown with rebels after Kelly leak

Gordon Brown is preparing for a showdown with rebel Labour MPs on the day the Commons returns from its summer break.

Supporters of the Prime Minister suspect there will be an orchestrated attack on his leadership at the private meeting of the Parliamentary Labour Party. It will be the first mass gathering of MPs since the resignations of dissidents including ex-whip Siobhain McDonagh, former vice-chairman Joan Ryan, envoy Barry Gardiner and minister David Cairns.

Hopes of a truce after Mr Brown's successful conference speech were shattered by anger at the leaking of Ruth Kelly's resignation plan - described as "a declaration of war" by one minister.

It is unclear whether Mr Brown will attend the PLP meeting - to be held after MPs get back on 6 October - because he may hold his Cabinet reshuffle then, but it would be wounding if rebels made a show of flouting his authority.

Meanwhile, tensions are rising in ministerial ranks amid claims that the Prime Minister plans a "Night of the Long Knives" to assert his authority.

The Evening Standard has learned that Justice Secretary Jack Straw and Chief Whip Geoff Hoon are among senior ministers advising him against culling suspected Cabinet rebels, a move MPs think would trigger civil war. Several ministers broke tradition by lobbying publicly to stay in their jobs. Foreign Secretary David Miliband said he wanted to keep his and friends said he would quit rather than accept demotion. Health Secretary Alan Johnson described himself as "deeply entrenched" in his department.

Die-hard Brown supporters are urging him to purge suspected plotters from the Government before they get a chance to resign on their own terms.

Some even want ministers to be subjected to a "loyalty test", in which they would have to promise allegiance privately in return for keeping their jobs.

Mr Straw is understood to believe there is no need to alter the Cabinet because it was refreshed only this year when Peter Hain resigned in a donations row.

He is said to be urging Mr Brown to limit the reshuffle to middle and junior levels, where fewer changes were carried out in the last big reshuffle 18 months ago.

A number of well-connected backbenchers are nervous that a big reshuffle would backfire, particularly if billed as Mr Brown stamping his authority. One ministerial aide said: "Reshuffles conceived to send out messages have a terrible track record of going disastrously wrong." Another insider said: "The public are worried about their jobs and their mortgages and they would not be very impressed if they see us fiddling around with our job titles."

Mr Brown is said to be agonising over how sweeping the reshuffle should be. He has no choice but to replace Ms Kelly and others, including business minister Lord [Digby] Jones, who want to leave. The Daily Mirror today claimed Welfare Secretary James Purnell, Communities Secretary Hazel Blears and Business Secretary John Hutton - all senior Blairites - could be in the PM's crosshairs.

Another rumour is that Mr Hoon could be replaced by deputy Nick Brown, a die-hard ally of the Premier. However, although Mr Hoon is keen to succeed Peter Mandelson as Britain's European Commissioner, a decision on that post cannot be taken until next year under European rules.