LONDON — Summoned by lawmakers to answer for a phone hacking and bribery scandal at one of his tabloids, Rupert Murdoch said he was humbled and ashamed Tuesday but accepted no responsibility for wrongdoing.

In a three-hour grilling, the 80-year-old media tycoon insisted he was at fault only for trusting the wrong people at the now-defunct News of the World, and noted that the paper made up a tiny portion of his vast media empire.

The scandal has rocked Murdoch’s News Corp. and embroiled Britain’s top police officials, many journalists and politicians.

Murdoch appeared flustered at the beginning of Tuesday’s parliamentary hearing, turning frequently to his son James for answers. But he soon regained his trademark cool.

He said he had known nothing of allegations that staff at the News of the World tabloid hacked into cell phones and bribed police to get information on celebrities, politicians and crime victims, and that he never would have approved such “horrible invasions” of privacy.

In the face of lawmakers’ suggestions that his organization encouraged such behavior, he was unflappable – even after a protester rushed at him in the middle of the hearing.

He stayed seated when the man tried to throw a foam pie at him. A News Corp. attorney partially blocked the attack, and Murdoch’s 42-year-old wife slapped the prankster. After the protester was arrested, the billionaire simply shed his splattered suit jacket and continued answering questions.

The scandal has captivated audiences from America to Murdoch’s native Australia, and there’s more to come – only some of the nearly 4,000 people whose information was hacked are known, and the police investigation appears to be widening. Murdoch has already shut the News of the World, given up on buying a major British satellite television company and accepted the resignations of two top executives because of the scandal.

He said he had no plans to resign, but expressed contrition on behalf of News Corp.’s British newspaper division, News International.

“This is the most humble day of my career,” said Murdoch, a man once so politically powerful in Britain that former Prime Minister Tony Blair flew halfway around the world to secure his support as he launched the Labour Party’s bid for power in 1995.

The scandal began as a blip in 2005, when the News of the World published a story about Prince William suffering a knee injury. Royal officials became suspicious about what had been closely held data, and alerted police. An inquiry led to one of the paper’s reporters and a private investigator being jailed for intercepting communications.

The Guardian newspaper then found out that Murdoch’s papers had paid out more than $1.6 million to settle lawsuits involving allegations of eavesdropping on phone messages. The scandal became a crisis for News International this month with the revelation that News of the World had hacked into the phone of a 13-year-old murder victim, Milly Dowler, in hopes of getting material for news stories.

Occasionally punctuating remarks by slapping his hands down on the desk, Murdoch said he was “shocked, appalled and ashamed” at the hacking of Dowler’s phone, but he rejected that criminality had been endemic at the tabloid. He also said he had seen no evidence that victims of the Sept. 11, 2001, terror attacks were hacked, an allegation the FBI is looking into.

Murdoch said he had not been informed that his company had paid out big sums – $1.1 million in one case – to settle lawsuits by phone hacking victims.

Murdoch noted that News of the World represented less than 1 percent of his global media empire, which also includes the Fox TV network, 20th Century Fox film studio, The Wall Street Journal, the New York Post and three major British newspapers. He said he spoke to the News of the World’s editor only about once a month.

Blame, he said, rested with “the people I trusted … and then, maybe, the people they trusted.”

News International CEO Rebekah Brooks and Wall Street Journal publisher Les Hinton, former executive chairman of News International, have resigned, although Murdoch said he did not blame either of them for the scandal. Brooks and Cameron’s former communications chief, Andy Coulson – a former editor at News of the World – are among several people who have been arrested in the scandal, although no one has been charged with a crime.

James Murdoch, 38, apologized for the scandal, telling British lawmakers that “these actions do not live up to the standards our company aspires to.”

Brooks testified after the Murdochs, describing allegations of voicemail intercepts of crime victims as “pretty horrific and abhorrent.” She said she had been told by employees of the tabloid that allegations of phone hacking by News of the World journalists were untrue, and that she realized the gravity of the situation only when she saw documents lodged in a civil damages case by actress Sienna Miller last year.