Culture Secretary Jeremy Hunt has insisted he had behaved "scrupulously fairly" as he fought for his political life over claims that he secretly backed News Corporation's bid to take over satellite broadcaster BSkyB.
The Tory Cabinet minister told reporters as he left his home on Wednesday that he was going to be making a "very, very determined" effort to show that he acted with "total integrity" in his conduct of the process of deciding whether to approve the deal.
"I made my position very clear, I am going to be making a very, very determined effort to show that I behaved with total integrity and conducted this process scrupulously fairly," he said.
Hunt's remarks come after he requested an early date at the Leveson Inquiry into press standards to give evidence after claims that emails released yesterday showed that he acted as a "cheerleader" for the News Corp bid.
On Wednesday morning his adviser, Adam Smith, quit his job after admitting his "activities at times went too far".
Labour leader Ed Miliband called for Mr Hunt to resign, accusing him of "acting as a back-channel" for the Murdochs.
The row is set to intensify today as Labour prepares to face down David Cameron over the allegations at Prime Minister's Questions.
Cameron's own links to the Murdochs will also come under the spotlight following yesterday's evidence from James Murdoch at the inquiry.
The News Corp executive revealed that he and the Prime Minister had briefly discussed the BSkyB bid in December 2010 - two days after Business Secretary Vince Cable was stripped of his decision-making power on the takeover.
That was at a Christmas dinner hosted by News International chief executive Rebekah Brooks the PM attended on December 23, 2010.
Murdoch told the inquiry that he and Cameron mentioned what had happened.
"He reiterated what he had said publicly, which is that the behaviour had been unacceptable, and I imagine I expressed the hope that things would be dealt with in a way that was appropriate and judicial," he said.
"It was a tiny conversation ahead of a dinner where all these people were there, so it wasn't really a discussion."
The inquiry last night released a 163-page dossier of emails detailing contacts between the Culture Secretary's office and a senior executive at News Corp.
Labour said the documents showed that 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.
Miliband said: "He 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 back-channel for the Murdochs.
"He cannot stay in his post. And if he refuses to resign, the Prime Minister must show some leadership and fire him."
Hunt, speaking yesterday, 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 the 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."
Hunt was given responsibility for the BSkyB takeover bid, which would have given News Corp full ownership of the satellite broadcaster, after Mr Cable was secretly recorded telling reporters he had "declared war" on the company's chairman Rupert Murdoch.
Hunt has denied being a "cheerleader" for Rupert Murdoch, saying: "Before the process, I had my views on Murdoch like everyone has their views. Once I took on this quasi-judicial role things changed and then I was totally different.
"That was why I decided - because I had expressed views in the past, like many people have about the Murdochs and BSkyB - that it was important to get the advice of BSkyB and independent regulators and after consideration I followed that advice."
Labour claimed the cache of emails published yesterday revealed that Hunt had given News Corp privileged access to information relevant to his decision and had misled Parliament about the extent of his contacts with the company.
The dossier includes scores of emails from Frederic Michel, who was then News Corp's director of public affairs in Europe, in which he updated executives including James Murdoch on the progress of the bid.
News Corp was seeking to buy the 61% share in BSkyB it did not already own, but dropped the bid on July 13 last year after public outcry over the revelation that the News of the World hacked murdered schoolgirl Milly Dowler's phone.