Culture secretary Jeremy Hunt has defied Labour calls for his resignation following claims that he secretly backed News Corporation's bid to take over satellite broadcaster BSkyB.
Mr Hunt insisted that he had conducted the process of deciding whether to green-light the BSkyB bid with "scrupulous fairness" and wrote to the Leveson Inquiry asking to be given an early date to give his side of the story in formal evidence, the Press Association reported.
In a dramatic development on Tuesday, the Leveson Inquiry into press standards released a 163-dossier of emails detailing contacts between the culture secretary's office and a senior executive at News Corp.
Labour said the documents showed that Mr Hunt failed to fulfil his quasi-judicial role in relation to the proposed takeover, which he had promised to carry out in a "fair and even-handed" way.
And they said that David Cameron also had questions to answer, after News Corp executive James Murdoch told the Inquiry that he and the prime minister had briefly discussed the BSkyB bid in December 2010 - days after business Secretary Vince Cable was stripped of his decision-making power on the takeover.
Downing Street insisted that the culture secretary still had the prime minister's full confidence.
But Labour leader Ed Miliband said Mr Hunt must resign and warned Mr Cameron he too had "questions to answer".
"I myself have said all politicians, including Labour, became too close to the Murdochs but this is in a completely different league," said Mr Miliband.
"We have Jeremy Hunt engaging in detailed discussions with a party, News Corporation, that is bidding to take over BSkyB and he is supposed to be the impartial judge.
"There are also questions for David Cameron to answer because now we know that just after Vince Cable was stripped of responsibility for the BSkyB takeover and it was passed to Jeremy Hunt, he, David Cameron, was having discussions with James Murdoch and others.
"We need to know what happened in those discussions. So there are questions for Jeremy Hunt to answer, there are also questions for David Cameron, George Osborne and the whole government to answer."
In a statement Mr Hunt said: "Now is not a time for knee-jerk reactions. We've heard one side of the story today but some of the evidence reported meetings and conversations that simply didn't happen.
"Rather than jump on political bandwagon, we need to hear what Lord Justice Leveson thinks after he's heard all the evidence.
"Let me be clear my number one priority was to give the public confidence in the integrity of process. I asked for advice from independent regulators - which I didn't have to do - and I followed that advice to the letter.
"I would like to resolve this issue as soon as possible which is why I have today written to Lord Justice Leveson asking if my appearance can be brought forward. I am very confident that when I present my evidence the public will see that I conducted this process with scrupulous fairness."
The calls for Mr Hunt's resignation followed the release of the dossier detailing contacts between the culture secretary's office and senior News Corp executive, Frederic Michel.
In a series of emails to James Murdoch and other executives, Michel - then the company's director of public affairs in Europe - reported on Hunt's thoughts about the progress of the controversial takeover plans, which were dropped in July last year amid the furore over phone-hacking at the News Corp-owned News of the World.
Another email, dating from January last year, reported Mr Hunt's belief that it would be "game over" for opponents of the BSkyB takeover once plans to spin off Sky News into a separately listed company were publicly announced.
"He said we would get there at the end, and he shared our objectives," Michel noted.
Although many of the emails refer directly to Michel having spoken to "JH", he told the inquiry that in fact this was shorthand for contacts with the culture secretary's office - usually his special adviser, Adam Smith.
The Labour leader said Hunt had been shown to be "acting in the interests of the Murdochs, not the British people" and should resign.
"He himself said that his duty was to be transparent, impartial and fair in the BSkyB takeover. But now we know that he was providing advice, guidance and privileged access to News Corporation. He was acting as a backchannel for the Murdochs," he said.
"He cannot stay in his post. And if he refuses to resign, the prime minister must show some leadership and fire him."
Raising a point of order in the Commons, deputy Labour leader and shadow culture secretary Harriet Harman said Mr Hunt's conduct had fallen "woefully short" of the standard expected.
She called on him to apologise to the Commons and resign from David Cameron's Cabinet.
"In view of the evidence that has been adduced before the Leveson Inquiry today it appears that the secretary of state has fallen woefully short of the standards expected by his office and by the public interest," Harman told MPs.
"I believe, on a point of order, that the right thing for the secretary of state to do would be to come to this House to offer an apology and to tender his resignation."
But Downing Street insisted that the culture secretary still had the prime minister's full confidence.