Culture Secretary Jeremy Hunt sought "private advice" from News Corporation over phone hacking, an email given to the Leveson Inquiry has suggested.
The previously unseen email, sent to ex-News International boss Rebekah Brooks by the firm's PR chief Frederic Michel, says Mr Hunt wanted "guidance".
Mr Hunt's spokeswoman said the claim was "inaccurate", but Labour said it was "collusion".
Meanwhile, police probing phone hacking have passed two files to prosecutors.
The latest documents relate to allegations of misconduct in a public office by police officers, the Crown Prosecution Service said.
The email to Mrs Brooks emerged while she was giving evidence on Friday to Lord Justice Leveson's inquiry into media ethics.
The last line of Mr Michel's email reads: "JH is now starting to looking to phone hacking/practices more thoroughly and has asked me to advise him privately in the coming weeks and guide his and No 10's positioning…"
BBC political editor Nick Robinson says that it is already known that Mr Michel often referred to "JH", meaning Jeremy Hunt, even when he had only spoken to Mr Hunt's special adviser Adam Smith.
Mr Smith has since resigned, saying that he had acted without Mr Hunt's authority, after it emerged he and Mr Michel had been in contact over News Corp's bid to take control of BSkyB - which was later dropped.
Mr Hunt was the cabinet minister tasked with deciding if such a takeover could go ahead.
The culture secretary himself has said he "strictly followed due process" in the matter, and denied that News Corp had any "back channel" of influence with his office.
In Mr Michel's email which he sent to Mrs Brooks on 27 June 2011, he mentions a tip-off about an "extremely helpful" statement the culture secretary was making to Parliament on phone hacking in relation to the BSkyB bid.
He wrote: "He [Mr Hunt] will be repeating the same narrative as the one he gave in Parliament few weeks ago.
"This is based on his belief that the police [are] pursing things thoroughly and phone hacking has nothing to do with the media plurality issues."
Referring to this latest disclosure, Mr Hunt's spokeswoman said Mr Michel had said before that he was not speaking to Jeremy Hunt, but to his special adviser, Adam Smith.
"It's widely acknowledged that he has exaggerated," she said.
The spokeswoman said Mr Hunt would respond to all emails and any other allegations when he gives evidence at the Leveson Inquiry in the next few weeks.
Downing Street has said there are "no plans" to investigate whether Mr Hunt has broken the ministerial code, with Prime Minister David Cameron saying Mr Hunt had acted properly and that it was a matter for the Leveson Inquiry.
Labour's shadow culture secretary, Harriet Harman, told the BBC: "What Fred Michel says in his emails, that Jeremy Hunt is subsequently going to do, exactly that happens.
"So either we've got to believe that Fred Michel is clairvoyant and telepathic, or else he was told and was in collusion with Jeremy Hunt. It's evidently the latter, and Jeremy Hunt is not fit to be doing his job."
During questioning at the Leveson Inquiry on Friday, Mrs Brooks said she discussed News Corp's bid to buy BSkyB with Chancellor George Osborne.
She said she made use of a social dinner with Mr Osborne to discuss opposition being put forward by the regulator Ofcom - and then emailed his response to Mr Michel.
During the hearing, Mrs Brooks was also asked about the amount of contact she had with senior UK politicians.
She was asked whether Mr Cameron had sent her a "keep your head up" message when she resigned she said it had been "something along those lines".
She said the prime minister signed off most texts with the letters DC but occasionally used the acronym LOL.
But she said he stopped this when he learnt the text shorthand stood for "laugh out loud" not "lots of love".
Mrs Brooks also said she received "indirect" rather than direct text messages from a number of politicians after she quit News International in the midst of the phone-hacking scandal in July 2011.
She told the inquiry she received messages from "Number 10, Number 11, the Home Office and the Foreign Office" as well as former Prime Minister Tony Blair.
The phone-hacking scandal at the News of the World led to its closure and the establishment of the Leveson Inquiry, an MPs' inquiry and the launch of three police investigations.
Mrs Brooks has denied any knowledge of phone-hacking on her watch.
She was arrested on 17 July 2011 over phone-hacking and corruption allegations.
She was released on bail and re-arrested on 13 March 2012, on suspicion of conspiracy to pervert the course of justice, and bailed again to appear at a London police station in May 2012.
The inquiry is currently looking at the relationship between the media and politicians, and will hear evidence on Monday from former No 10 press secretary Alastair Campbell.