In full: Dominic Grieve's letter

I am writing in view of your recent public comments in relation to the arrest of Damian Green. You have asserted that the operational independence of the police prevents you from publicly commenting on any aspect of his arrest and the raids on four business and residential properties, including his House of Commons office.

Your reliance on this principle as blanket cover to avoid giving any public comment on the operation is misplaced and inconsistent. It is one thing to leave the police to conduct an independent investigation impartially and faithfully, which we can agree on. It is another to suggest that there should be no ministerial oversight of - or comment on - police operations whatsoever. Since 1997, Home Secretaries have consistently commented on police operations in the interests of transparency and sustaining public confidence. Your predecessor commented on the handling of Operation Overt in the aftermath of the failed terrorist attack at Heathrow, provided public updates on the investigation after the death of Alexander Litvenenko and publicly defended the police operation at Forest Gate in June 2006. You have followed the same approach, for example, issuing a press release on 29 November 2007 in relation to the arrest of 118 people following a police operation against gun crime.

However, in the case of Damian Green, you have failed to give a full and frank account of your own state of knowledge, and refused to give a view on whether the police raid on 27 November, involving counter-terrorism police, was heavy-handed. Your silence on these matters is incomprehensible and indefensible.

So too, you have failed to give a categorical assurance that neither you, Ministers nor any Home Office officials were aware that Damian Green or any other Member of Parliament were the subject of the police investigation following the arrest of a junior Home Office civil servant on 19 November. This is astonishing, given that your department referred the leaks for an inquiry in the first place, and were well aware from the relevant newspaper coverage that the Shadow Home Affairs team had commented on the fiascos at your department revealed through the leaks.

The only plausible conclusion for your failure to give this assurance is that you were aware that Damian Green, or another Member of Parliament, was the subject of the investigation - conducted not under the Official Secrets Act, but an antiquated common law misconduct offence. In these circumstances, it appears that you failed to ask even the most basic questions about who was involved and the handling of an operation with the obvious potential to create considerable controversy and undermine public confidence - questions which would not have impinged in any way on the police carrying out a proper investigation. At the very least you might have asked whether the police had asked to question Damian on a voluntary basis, why it was necessary to dispatch counter-terrorism police officers and clarified the grounds and procedure followed for the search and seizure operation at Damian's House of Commons office. You have utterly failed to exercise the most basic Ministerial oversight over counter-terrorism police that is essential in a democratic country.

Having clung to the principle of operational independence to avoid answering the most basic questions, you have nonetheless seen fit to encourage speculation about the true nature of the allegations facing Damian. During your interview on The Andrew Marr Show, yesterday, it was put to you that it was not appropriate to have such a heavy-handed police operation to deal with leaks that were politically embarrassing without jeopardising national security. You replied:

'You don't have the evidence that the police are looking at the moment. Neither do I ... This was about a series of breaches of security in a department that deals with some of the most confidential and sensitive information across government - a systematic series of leaks ... This is not about politicians being able to use information that they come across to hold the Government to account, even to embarrass the Government.'

Given media reporting that the police may have suspected Damian was 'grooming' a source in the Home Office through some form of inducement, your insinuation was deeply irresponsible. Damian adamantly denies this suggestion, and no evidence has been presented to demonstrate any grounds for such a suspicion. Equally, not one of the identifiable leaks involves official secrets or national security.

You have avoided answering the most basic, legitimate, questions about this disturbing episode, whilst fuelling inference and rumour. It is now imperative that you urgently provide a full account of your state of knowledge about the subjects of the investigation, as well as that of officials at the Home Office.

In view of the widespread interest in this matter, I will be making this letter publicly available.