News Corp. (NWSA) Chairman and Chief Executive Rupert Murdoch wrapped up three hours of testimony before a parliamentary committee on Tuesday by stressing how the phone hacking scandal rocking his global media empire has struck him personally.

This is the most humble day of my career, he said.

Murdoch apologized to people whose phones had been hacked by reporters for the British tabloid News of the World, especially those who were victims of crime. To those people Murdoch said he is completely and deeply sorry.

The hearing was abruptly shut down when a man, later identified as a British comedian, approached Murdoch and attempted to push a plate of white cream into his face. After a brief scuffle, the man was escorted from the room and taken into police custody.

When the hearing started up again a few minutes later, Murdoch appeared unruffled but without his suit coat.

Murdoch and his son James, also a top News Corp. executive, testified before the parliamentary committee seeking answers as to how and why the practice of hacking the phones of celebrities, politicians and private citizens endured and who knew about it at the top levels of the company.

The scandal has badly shaken media, legal and political institutions in Britain.

Rupert Murdoch told the committee members that he was shocked, appalled and ashamed by the allegations. His wife Wendy sat directly behind him during his testimony and she could be seen leaping at the man who struck her husband with the plate of foam.

James Murdoch said company executives became aware of the scope of the practice toward the end of 2010. As soon as we had that new information & we acted on it immediately, he said.

The scandal has been well documented in Britain for nearly a decade, and News Corp. has acknowledged paying out large sums in settlements to people who sued the company citing invasion of privacy. But for years company executives had blamed the scandal on a few rogue employees.

The scandal exploded several weeks ago and public outrage escalated when the lawyer for the family of an abducted and murdered 13-year-old girl claimed the girls phone had been hacked. Since then, others including a former prime minister have come forward with similar accusations.

Two weeks ago, News Corp. shuttered News of the World, its oldest British property, as the scandal expanded. The resignations of several top News Corp. executives, including Rebekah Brooks, who once edited News of the World, and Les Hinton, who was currently running the companys Dow Jones operations, followed.

In addition, two prominent police officials in Britain have resigned as part of the scandal in the wake of allegations that News Corp. employees bribed police in order to obtain confidential material to feed scoops.

During Tuesdays hearings, James Murdoch said he was familiar with the term willful blindness, a legal term raised by one of the parliament members, but the younger Murdoch said didnt see any connection to the current proceedings.

Rupert Murdoch cut in, We were not ever guilty of that.

The term was often used during the Enron scandal in the U.S. a decade ago, when top Enron officials said they were unaware of the criminal activities taking place in executive suites below their lofty perches.

At another point in the hearing, Rupert Murdoch said he spoke often with editors in Britain, including the top editor of News of the World. But he said was not told about large settlement payments made to those who sued the paper for invasion of privacy stemming from the hacking of their phones.

The elder Murdoch said he may have lost sight of the News of the World because its so small within the company.

But Rupert Murdoch insisted he is not a hands off manager. To the contrary, he said.

News Corp.s shares were up 80 cents, or 5.3%, at $15.76 in midday trading.

The scandal jumped across the Atlantic this week and impacted News Corp.s U.S. operations. On Monday ratings firm Standard & Poors placed the companys shares on CreditWatch with negative implications. 

In a statement, S&P said the decision was based on the increased business and reputation risks associated with (News Corp.s) broadening legal inquiries.

In our opinion this and other recent developments materially increase the reputational, management, litigation, and other risks currently faced by News Corp. and its subsidiaries, Standard & Poor's credit analyst Michael Altberg wrote.

Also, the FBI has said its looking into allegations that phone hacking may have taken place in the U.S.

On Tuesday, Moody's came out with its own report, saying it does not expect the phone-hacking issue to impact its credit rating on News Corp.

Follow Dunstan Prial on Twitter @DunstanPrial