PM insists cops will investigate all evidence

The PM has become uncomfortably mired in the scandal himself due to his close friendship with former News International chief executive Rebekah Brooks, who was this week officially charged by police.

Ms Brooks and her husband Charlie, an old school friend of Mr Cameron, were charged with conspiracy to pervert the course of justice.

The couple vowed to fight the allegations in court and attacked police and prosecutors over what Ms Brooks claimed was "an expensive sideshow and a waste of public money."

Asked whether he was upset by the action against the Brookses, the PM said the justice system had to take its "proper course."

Mr Cameron who has faced criticism over his social engagements with Ms Brooks, told ITV1's Daybreak: "I think it's very important that the police, the justice authorities, that they follow the evidence wherever it leads and they take all the action.

"They are independent in this country, they don't obey the orders of the government and that's the way it should be. So that has to take its proper course and its natural course."

He said there were "big lessons to learn from all of this" and suggested that politicians had not tackled issues of media regulation properly in the past because of their closeness to the press.

A number of senior government figures including the PM have been called to testify at the Leveson phone hacking inquiry over allegations of inappropriate links with News Corporation.