Wendi Deng (2nd L) lunges towards a man trying to attack her husband, News Corp Chief Executive and Chairman Rupert Murdoch, during a parliamentary committee hearing on phone hacking at Portcullis House in London July 19, 2011.(Agencies)

Click for video of the hearing

Rupert Murdoch, unfazedby a foam pie attack in the British parliament, made a "humble" apology on Tuesday for crimes that have rocked his media empire and the government but refused to resign, saying the fault lay with staff who "betrayed" him.

Revelations of phone-hackingand payments to police by the News of the World have raised questions on his family's grip on News Corporation, on the probityof the police and on the judgment of Prime Minister David Cameron, who returned early from Africa for an emergency parliament debate on Wednesday.

Calling it "the most humble day of my life", Murdoch defended his record and that of his son, and said he could not know everything that his 53,000 employees did. James, 38, sat beside him before parliament's media committee, interjectingon occasion as his 80-year-old father hesitated to give answers on what he knew, and when, of criminality at the Sunday tabloid.

But as three hours of earnest, at times testy, proceedings drew to a close with lawmakers pressing the Murdochs to explain payments to some of those involved in the decade-old affair, the hearing briefly turned to violence and farcewhen a man rose from the public seating of the packed committee room.

As he tried to hit the elder Murdoch with a paper plate of white foam, the Australian-born mogul's 42-year-old wife Wendi Deng leapt in to slap the protester in a meleebefore he was seized by police. He was identified as a left-wing comedian.

After a short recess, Murdoch, now jacket-less, was told by one of the committee members he had shown "immense guts". Another lawmaker, long one of his most bitter critics, later jokingly complimented his wife on her "very good left hook".