Culture Secretary Jeremy Hunt has come under renewed pressure following the publication by the Leveson Inquiry of a memo in which he made private representations to the Prime Minister supporting News Corporation's bid to take over BSkyB.
The document, sent just weeks before Mr Hunt was given quasi-judicial oversight of the bid, warned that News Corp's James Murdoch was "furious" about Business Secretary Vince Cable's handling of the matter.
Dated November 19 2010, the note to David Cameron expressed concerns that referring the bid to Ofcom could leave the Government "on the wrong side of media policy".
But Downing Street played down its significance, pointing out that Mr Hunt had already made supportive comments about the bid in press interviews earlier that year.
A Number 10 spokesman said: "Jeremy Hunt's note is entirely consistent with his public statements on the BSkyB bid prior to taking on the quasi-judicial role. It also makes clear that 'it would be totally wrong for the Government to get involved in a competition issue which has to be decided at arm's length'.
"The PM has made clear throughout that he recused himself from decisions relating to BSkyB and did not seek to influence the process in any way."
A source close to Mr Hunt also said there was nothing in the memo that suggested he should not have been given the quasi-judicial function when it was stripped from Mr Cable in December 2010.
"Jeremy is clear in the memo, as he was throughout the bid process, that it should only go ahead if it addressed the plurality concerns," said the source.
The dramatic disclosure of the memo came as Mr Hunt's former special adviser, Adam Smith, gave evidence to the Leveson inquiry into media standards.