DAVID Cameron has made clear he is standing by his Culture Secretary as No 10 rejected Labour calls for John Whittingdale to stand aside from making decisions about press regulation after revealing that he had a relationship with a prostitute.

Downing Street confirmed that the Secretary of State did not inform the Prime Minister about press interest in his relationship with the so-called "dominatrix" when he was appointed to the Cabinet after the 2015 general election.

It said Mr Cameron only learned about the affair some 10 days ago when the story emerged on the internet. His spokesman said it was a decision for Mr Whittingdale whether or not he felt it necessary to inform the PM about the issue.

Asked if the PM should have been told, he replied: “John Whittingdale’s view was that this was in the past and had been dealt with.”

He added: “The Prime Minister has got full confidence in John Whittingdale to perform all his duties.”

But the Essex MP faced calls from campaigners and Labour to “recuse” ie withdraw himself from decisions about press regulation amid claims that the revelations had left him vulnerable because there was a perceived conflict of interest.

Although the relationship occurred before he was made a minister following the General Election, he was at the time chairman of the influential Commons Culture, Media and Sport Committee, which had held a series of high-profile hearings on the phone-hacking scandal.

It emerged that four newspapers - The People, The Mail on Sunday, The Sun and The Independent - had investigated the claims at the time but concluded it was not a public interest story.

Mr Whittingdale insisted that events had no bearing on any decisions he had taken in office.

"This is an old story which was a bit embarrassing at the time,” he declared. “The events occurred long before I took up my present position and it has never had any influence on the decisions I have made as Culture Secretary."

But Maria Eagle, his Labour shadow, said it was essential that Mr Whittingdale acted to ensure there was no perception of "undue influence" in his dealings with the press.

"Everyone is entitled to a private life. However, these revelations raise serious questions about why the Secretary of State has reneged on the Government's promise to deliver the cross-party agreement on Leveson when this is something he was previously committed to as chair of the Culture, Media and Sport committee," she said.

"For the public to have any confidence in the Government's approach to press regulation and to allay any concerns about perceptions of any undue influence, the Secretary of State must now recuse himself from any decision-making over this matter, just as Vince Cable was removed from deciding media policy in the last parliament."

The ministerial code of conduct for ministers says they “must ensure that no conflict arises or appears to arise between their public duties and their private interests”. The PM’s spokesman said he did not believe there was any perception of a conflict of interest.

Mr Whittingdale’s Conservative colleague, Liam Fox, the former Defence Secretary, hit back at Labour, tweeting: “Unbelievable hypocrisy from @labour on @JWhittingdale. The fact papers didn't run story in first place shows press regulation is working.”

Meantime, Brian Cathcart, from the Hacked Off campaign group, said Mr Whittingdale was “compromised”, adding that he thought the newspapers had "stocked up" the story for future use as a way possibly to put "pressure on him".

But Bob Satchwell for the Society of Editors argued that it was a "preposterous conspiracy theory too far" to say newspapers and broadcasters "jointly decided not to publish" the story.