LONDON (Reuters) - Rupert Murdoch said on Monday he had never asked a British prime minister for anything, seeking to play down his influence ahead of what is likely to be a politically charged approval process for his $14.6 billion bid for pay-TV group Sky (>> SKY PLC).

The 85-year-old's Twenty-First Century Fox (>> Twenty-First Century Fox Inc) made a formal approach to take full control of the British-based Sky last week, reigniting a row over whether the media mogul controls too much of Britain's media and had too much sway over politicians.

In a short letter to the Guardian newspaper on Monday, Murdoch rejected the suggestion that he had once said: "When I go into Downing Street, they do what I say; when I go to Brussels, they take no notice,".

"There is much fake news published about me," he said. "Let me make clear that I have never uttered those words. I have made it a principle all my life never to ask for anything from any prime minister."

The letter, signed "Rupert Murdoch, New York, USA", was published on the Guardian website.

Murdoch's previous attempt to buy the 61 percent of Sky he did not already own was scuppered in 2011 by a phone-hacking scandal at one of his tabloid newspapers.

The British government will have to decide in the new year whether to refer the new bid for further scrutiny by the media regulator Ofcom.

Murdoch's statement that he had never sought to influence prime ministers is in contrast to evidence one former British premier gave to a public inquiry into media standards sparked by the phone-hacking revelations in June 2012.

Former Prime Minister John Major recounted how he had had dinner with Murdoch before the 1997 national election and said the media mogul had tried to change his policy on Europe.

"It is not very often someone sits in front of a prime minister and says to a prime minister: 'I would like you to change your policy, and if you don't change your policy, my organization cannot support you'," Major told the inquiry headed by judge Brian Leveson.

Andrew Neil, a former editor of the Murdoch-owned Sunday Times newspaper, told the same inquiry that Murdoch had used support for Tony Blair's Labour government as a means of securing changes to media ownership rules which made his current bid for Sky possible.

"When Mr Murdoch testified before this inquiry that he had never asked government for anything it gave me cause to wonder if he had forgotten this - or forgotten he was testifying under oath," Neil said.

(Reporting by Kate Holton and Michael Holden; editing by Stephen Addison and Adrian Croft)

Stocks treated in this article : SKY PLC, Twenty-First Century Fox Inc