Prime Minister Tony Blair has rejected demands for an inquiry into claims by Britain's senior anti-terror police chief that leaks have placed lives at risk.
Tory leader David Cameron challenged the Prime Minister to set up an immediate inquiry into Scotland Yard's suggestion that culprits were trying to "squeeze out some short-term presentational advantage" by secretly briefing on anti-terror operations.
Commentators interpreted the remarks by Metropolitan Police Assistant Commissioner Peter Clarke as an attack on the Government's army of special advisers, or "spin doctors", who have been accused of trying to score political points from terror investigations.
Mr Cameron asked Mr Blair to guarantee that the leaks had not come from either ministers or special advisers.
The Prime Minister said they had not come from those sources "as far as I am aware", adding that he would "completely condemn" any such leaks and would hold a full investigation if there were any evidence.
Mr Cameron asked: "If you don't have a leak inquiry, how on earth can you know?"
The Liberal Democrats also called for an investigation into the leaks. The party published a dossier of dozens of off-the-record briefings on terrorism issues referred to by newspapers over the past five years.
It included a list of comments by "Whitehall sources" - the phrase used by journalists when an official in the security services, Government, police or another official capacity does not wish to be named.
Lib Dem home affairs spokesman Nick Clegg said: "As our dossier on the numerous cases in which so-called 'Whitehall sources' have sought to provide a spin on ongoing terror investigations shows, there is now real evidence that the Government's culture of spin is undermining rather than strengthening our collective response to the terror threat.
"The source of the leaks referred to by Peter Clarke should be investigated urgently."
