The committee told Brooks, who was arrested last week, it would be careful with its probing because she is participating in a criminal investigation. She insisted that she did not know about the extent of the phone hacking.
"We had been told by people at News of the World at the time -- they consistently denied any of these allegations in various internal investigations," she said.
She told the committee she acted "quickly and decisively" in dealing with the phone hacking scandal at the News of the World once she had seen fresh evidence regarding actress Sienna Miller in December 2010.
She also denied reports that she had an overly influential relationship with the current and previous prime ministers.
"I have never been horse riding with the prime minister," she said in response to various news reports about her close relationship with Prime Minister David Cameron. Cameron hired a previous News of the World editor, Andy Coulson, a former editor of the News of the World who was arrested earlier this month, as communications director in 2007.
Brooks said she "regularly" visited former Prime Ministers Tony Blair and Gordon Brown at Downing Street around six times a year.
Earlier, Rupert Murdoch told the British Parliament committee that he wasn't responsible for the scandal that has embroiled his media empire.
"Mr. Murdoch, do you accept you are ultimately responsible for this whole fiasco?" asked Jim Sheridan, a member of Parliament.
"No," replied Murdoch, explaining that those he hired and trusted and the people who they hired and trusted were responsible. He mentioned Les Hinton, the publisher of the Wall Street Journal, who resigned Friday. Hinton and Murdoch have worked together for 52 years, including while Hinton was chief executive of News International, Murdoch's British newspaper publisher.
"I would trust him with my life," Murdoch said of Hinton.
The House of Commons Culture, Media and Sport Committee opened hearings into the phone hacking scandal that has roiled the media, police and the public in Britain. Outside the hearing room, the international media and a huge crush of spectators crowded the building. Behind the Murdochs sat a limited number of spectators, including Murdoch's wife, Wendi Deng.
The morning's questioning is a follow-up to a similar hearing that took place in 2009. In the committee's previous report, the committee stated it was "inconceivable" only one reporter had been involved in phone hacking.
When asked if closing News of the World was a commercial decision, Rupert Murdoch said, "Far from it."
Both men played down the suggestion that they were planning to open a new Sunday tabloid to replace the News of the World.
"We have made no decision on that," Rupert Murdoch said. His son added: "I think we leave all those options open. That is not the company's priority now."
Rupert Murdoch's first comment to Parliament was that today is the "most humble day of my life."
In answering a query about his hands on-off approach when it comes to his newspapers, Rupert Murdoch said that he perhaps "lost sight of" the News of the World because it was so small in the general frame of the company. He explained that the editor he is in most touch with is the editor of the Wall Street Journal because they work in the same building. The News Corp. headquarters is in Manhattan.