LONDON - BRITISH police announced on Tuesday a review into their handling of a probe into political leaks which triggered the arrest of a top opposition lawmaker - and a major constitutional storm.

Mr Damian Green, immigration spokesman for the main opposition Conservatives, was held for nine hours last Thursday, while London's Metropolitan Police also searched his House of Commons and constituency offices.

The move has prompted furious claims that British Prime Minister Gordon Brown's Labour Party, which has been trailing the Conservatives in opinion polls for months, may have been behind the 'Stalinist' move.

Police say they arrested Mr Green, who denies any wrongdoing, on suspicion of 'conspiring to commit misconduct in a public office', while officers also held a junior civil servant, Chris Galley.

Now the Met's acting head Paul Stephenson has asked Ian Johnston, the head of the British Transport Police and a leading figure in the Association of Chief Police Officers (ACPO), to deliver an interim report within one week and a full report in two.

The announcement shows no sign of calming the furious debate, particularly over the police search of Green's office in parliament, which has been making headlines in Britain since the end of last week.

Home Secretary Jacqui Smith has declined to apologise, saying she was unaware the senior Conservative would be arrested until after it happened and police should be able to follow the evidence in a case wherever it leads them.

But Mr Dominic Grieve, home affairs spokesman for the Conservatives, has accused her of 'washing her hands' of any responsibility.

'It would have been Stalinist and wrong if she had sought to direct the police operationally,' he told BBC radio on Monday.

'It was part of her job to ask searching questions and make sure that procedures were being properly followed before police decided to erupt into the Houses of Parliament.'

House of Commons Speaker Michael Martin, who has faced heavy criticism from those who say he should have stopped police from entering the so-called mother of parliaments, is due to make a statement to the Commons on Wednesday.

Mr Nick Clegg, leader of the opposition Liberal Democrats, said: 'If we let the Damian Green incident just pass, I think we'll go down a slippery slope of letting the government do whatever it likes between one election and the next.'

But Mr Brown said nobody was above the law including lawmakers, and insisted the police should be left free to complete their investigation.

'There is going to be a time when all these things are going to be investigated and reviewed after the police have finished their work and MPs, of course, have got to be allowed to get on with their job,' he said.

'But no MP is above the law. There has got to be operational independence for the police. The police have got to be able to get on with their job without interference by politicians.'