Tory immigration spokesman Damian Green has pointed the finger of blame at ministers after he was told he will not face charges in the Home Office leaks inquiry.
Mr Green, who was arrested in November, said he was "very pleased" with the decision of the Crown Prosecution Service.
But he said the failed investigation reflected an "out of touch, authoritarian, failing government".
The ruling raises serious questions about the decision to call in police, which was made at the highest levels of the civil service.
Director of Public Prosecutions Keir Starmer said neither Mr Green nor Christopher Galley, the civil servant who passed him a string of confidential documents, would face charges.
Mr Starmer said the material did not relate to "military, policing or intelligence matters" and was not in many ways "highly confidential".
His statements appeared to contradict claims by senior civil servants relating to the decision to call in Scotland Yard.
In the letter to police which prompted the investigation, Cabinet Office director of security and intelligence Chris Wright said the leaks had caused "considerable damage to national security".
Sir David Normington, the most senior civil servant in the Home Office, told a committee of MPs that "at least one" of the leaks related to national security.
Home Secretary Jacqui Smith defended the role of the Home Office in the leaks inquiry and insisted it would have been "irresponsible" not to have taken action.
Read More
MORE ABOUT