A high-level parliamentary committee looking into allegations of phone-hacking against Rupert Murdoch’s British newspaper group, News International, on Thursday descended into an extraordinary personal exchange when Tom Watson, a senior Labour MP, likened its chief executive James Murdoch to a “mafia boss” who pretended not to know that he was running a “criminal enterprise”.

Half-way through the two-and-a-half hour tense hearing that saw MPs grill Mr. Murdoch over how much he knew about the extent of hacking on the now defunct News of the World, Mr. Watson dramatically turned to him and asked if he was familiar with the code of “omerta”.

Mr. Watson then explained to a puzzled Mr. Murdoch that it characterised “a group of people bound together by secrecy who together pursue their group’s business objectives with no regard for the law”.

“Is that an accurate description of News International in the U.K.,” he asked.

To Mr. Murdoch’s retort that such a suggestion was “offensive”, Mr. Watson leaned forward and said: “You must be the first mafia boss in history who didn't know he was running a criminal enterprise.”

“Mr. Watson, please!” said Mr. Murdoch describing the remark as “inappropriate”.

Mr. Watson has pursued News International after his own phone was hacked. It has also since emerged that he was among a large number of high-profile figures secretly followed by a private detective detailed by NoW.

Mr. Murdoch profusely apologised to Mr. Watson and others who may have been subjected to “surveillance” saying it was “absolutely not acceptable”.

Mr. Murdoch, who previously appeared before the committee with his father in July, had been recalled following claims that he misled it then. Mr. Murdoch insisted he stood by his July testimony.

At the heart of the dispute is an email showing that hacking at NoW went beyond one “rogue” correspondent, its royal editor Clive Goodman who was jailed in 2007. Mr. Murdoch denies he was ever shown that email or told about its contents but his account is disputed by two former senior News International executives — former legal manager Tom Crone and NoW’s former editor Colin Myler — who claim that the email was discussed with Mr. Murdoch during a meeting at which he approved compensation payment to a hacking victim.

Mr. Murdoch stuck to his version on Thursday and, instead, accused Mr. Crone and Mr. Myler of “misleading” the committee.

Mr. Murdoch said if he had known more about the email “the company would have acted differently”.

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