Rebekah Brooks said yesterday that she was a friend of the Prime Minister but denied she had influenced his appointment of Andy Coulson as his party's director of communications.
"The truth is that he is a neighbour and a friend but I deem the relationship to be wholly appropriate," she said.
The newly resigned chief executive of News International denied Press reports that she had gone riding with David Cameron or spoken to him about the appointment of Mr Coulson - or that NI had augmented Mr Coulson's salary while he worked at Conservative Central Office.
Asked whether she had ever spoken to Mr Cameron about Mr Coulson prior to his appointment, Ms Brooks replied: "That is not true. Never was true."
Appearing before the Commons Culture, Media and Sport Committee's investigation into phone hacking, the former tabloid editor said that the News of the World had repeatedly assured her that allegations the newspaper used the practice were untrue.
"They consistently denied any of these allegations in various internal investigations," she said.
"It was only when we saw the Sienna Miller documentation that we realised the severity of the situation."
She agreed that the NoTW used private detectives. Pressed by Labour MP Tom Watson, she added: "I was aware that the News of the World used private detectives, as every paper in Fleet Street did. The payments would have gone through the managing editor's office."
However, Ms Brooks denied she had met ever Glenn Mulcaire, the private detective exclusively contracted to the NoTW, who was jailed in 2007 for hacking into the Royal household.
"I didn't know particularly that Glenn Mulcaire was one of the detectives that was used by the News of the World," she said.
"In fact, I first heard Glenn Mulcaire's name in 2006."
Asked about her links with private investigator Jonathan Rees, a convicted criminal, she replied: "He wasn't a name familiar with me, I am told that he rejoined the News of the World in 2005, 2006, and he worked for the News of the World and many other newspapers in the late 1990s."
Asked whether she found it "peculiar" that Rees had been rehired after serving a sentence for a very serious offence, she replied: "It does seem extraordinary."
She struggled to name other private detectives who had worked with the News of the World. "It isn't that I can't remember, it's that you have the same information that I have, which is from Operation Motorman," she said.
Asked whether she had any regrets, she said: "Of course I have regrets. The idea that Milly Dowler's phone was accessed by someone being paid by the News of the World, or even worse authorised by someone at the News of the World, is as abhorrent to me as it is to everyone in this room.
"And it is an ultimate regret that the speed in which we have tried to find out the bottom of these investigations has been too slow."
Referring to her comments in 2003 that payments had been made to the police, she said: "I can say that I have never paid a policeman myself. I have never sanctioned, knowingly sanctioned, a payment to a police officer," she told the cross-party committee.
"In my experience of dealing with the police, the information they give to newspapers comes free of charge."