A former News International lawyer has accused company chairman James Murdoch of giving "disingenuous" evidence to an MPs' inquiry into phone hacking.
Mr Murdoch insisted he did not know until recently that the illegal practice went beyond a lone reporter at the News of the World.
But Tom Crone said he had made Mr Murdoch aware of the paper's wider involvement in hacking three years ago.
He said it was "regrettable" that Mr Murdoch felt the need to discredit him.
In his second appearance before the Commons culture committee, Mr Murdoch spoke of a key piece of evidence known as the "For Neville email" which contained transcripts of voicemail messages revealing that football union boss Gordon Taylor's phone had been hacked.
He denied being shown a copy of the email during a June 2008 meeting with Mr Crone, but said he was given "sufficient information to authorise" an increase in the out-of-court offer to Mr Taylor.
He said he was not told about the nature of the email nor of "evidence or suspicion of wider spread wrongdoing".
However, in a statement released just hours after the hearing, Mr Crone said it was "regrettable", but he could "perfectly understand" why James Murdoch felt the need to discredit him and former editor Colin Myler.
"The simple truth is that he was told by us in 2008 about the damning email and what it meant in terms of wider News of the World involvement.
"It seems he now accepts he was told of the email, of the fact that it contained transcripts of voicemail interceptions and that those interceptions were authorised by the News of the World.
"Perhaps Mr Murdoch could explain who he thought was doing the authorising at the News of the World?
"At best, his evidence on this matter was disingenuous."
During the hearing, Mr Murdoch was pressed by Labour MP Tom Watson on the discrepancies between his account of events, and that of Mr Crone and Mr Myler earlier this year.
Mr Murdoch disputed their claim that they "did inform" him of the email at the time, and accused them of being "inconsistent" and "misleading" the committee.
'Code of silence'
In his statement, Mr Crone said: "For the record, I did not 'mislead the committee' about the evidence being confined to a 'single rogue reporter'."
Mr Myler has also issued a statement, saying his evidence to MPs was "entirely accurate and consistent".
"I stand by my account of the meeting with James Murdoch on 10 June, 2008," he wrote.
He added that he was confident the ongoing police investigation and the Leveson inquiry - due to formally begin on Monday - would establish the truth.
Meanwhile, former NoW chief reporter Neville Thurlbeck, to whom the "For Neville email" is assumed to be referring, has denied accusations that he was involved in hacking.
He said he has compiled a dossier to clear his name, and that it would be good news for Mr Murdoch.
"I think there was a News of the World agenda which very firmly believed that a lid could be kept on all of this if everybody said nothing. I don't think a lot of the information went further than the News of the World newsroom floor," he said.
MPs, who are expect to present a report to the House of Commons by the end of the year, asked a wide range of questions.
About halfway through, Tom Watson - who has pursued the company over the phone hacking scandal - suggested its UK arm operated like the Mafia, adopting the "omerta" code of silence. Mr Murdoch dismissed this as "offensive and not true".
The MP went on to say the company was facing a series of allegations around hacking and told him: "You must be the first mafia boss in history who didn't know he was running a criminal enterprise."
Mr Murdoch said that was "inappropriate" and said while it was a "matter of great regret" that "things went wrong" at the newspaper, when evidence had come to light "we acted... with great zeal and diligence to get to the bottom of issues to improve the processes to make sure they didn't happen again".
The BBC News Channel's Norman Smith said it may never be known who has been telling the truth, but the whole saga has damaged the reputation of all those involved, including News International and Mr Murdoch himself.
He said there was a sense from the hearing that the chairman did not have a grip on what was going on, which will concern shareholders.
In July, the News of the World was shut down after it was found to have hacked into the voicemail messages of prominent people, including murdered teenager Milly Dowler. The Metropolitan Police estimate about 6,000 may have had their phones hacked since 2002.