Clarke's justice ministry 'could be broken up'

The Home Office would take back responsibilities for prison policy and a new department would be created for immigration, passport control and citizenship.

Justice Secretary Mr Clarke has been criticised for decisions relating to sentencing and prisons, infuriating many Tory backbench MPs for not being tougher.

Home Secretary Theresa May reportedly jokes: "I lock 'em up, Ken lets 'em out."

Downing Street insiders are said to be concerned at cultural clashes between the Home Office and the Ministry of Justice.

Officials at the Home Office - which is responsible for the police, counter-terrorism and immigration - are seen as being ready to adopt tough stances having worked for heavyweights including Labour's David Blunkett, John Reid and Charles Clarke. The Ministry of Justice, which was created out of the Lord Chancellor's Department, is viewed as far more liberal as it focuses on tackling re-offending, defending civil liberties and prisons.

"The Home Office is about controlling people, the Ministry of Justice is about giving people rights," one minister told The Times.

The reforms would aim to put law and order duties under one department.

Immigration minister Damian Green, who is respected on both wings of the Tory party, is being touted as a strong contender to jump into the Cabinet at the helm of the new department.

Mr Clarke's aides dismissed the idea that his department could be carved up. And a Downing Street spokesman said: "It's speculation. There's no grounds for that."

Ms May and Mr Clarke had a bust-up at last year's Tory conference when he cast doubt on her claim that a Bolivian immigrant could not be deported because he had a pet cat.

The Justice Secretary was also forced by No 10 to ditch plans for 50 per cent sentence discounts for early guilty pleas.

Ms May yesterday announced that the UK Border Agency will be split in two after an official investigation into the relaxation of border checks last year found poor record-keeping and ambiguous instructions were rife and that staff had acted without ministerial approval.

John Vine, the independent chief inspector of the UKBA, discovered that about 500,000 Eurostar passengers boarded trains in France and arrived in the UK without being checked against the warnings index of suspected terrorists.

He also found border security checks had been suspended regularly and applied inconsistently since at least 2007.