Rebekah Brooks, the embattled chief executive of media baron Rupert Murdoch's British newspaper operation, finally resigned on Friday after days of fierce pressure over the phone hacking scandal.

The flame-haired Brooks, 43, a former editor of the scandal-shut News of the World tabloid, told staff that she felt a "deep sense of responsibility" for the crisis which has now spawned an FBI probe in the United States.

"I have given Rupert and James Murdoch my resignation. While it has been a subject of discussion, this time my resignation has been accepted," Brooks, who originally offered her resignation last week, wrote in an internal message.

Her decision came after Murdoch finally broke his silence on a crisis which has forced him to shelve a buy-out of pay-TV giant BSkyB, close the News of the World, and allow himself to be questioned by British lawmakers.

Brooks will be replaced by Tom Mockridge, chief executive of satellite broadcaster Sky Italia, who faces a battle to restore the faith of readers and shareholders in Murdoch's stable of British newspapers.

News International runs The Sun, Britain's biggest selling daily newspaper, The Times and the Sunday Times. It closed down the 168-year-old News of the World on Sunday in a vain bid to save Murdoch's bid for pay-TV giant BSkyB.

Prime Minister David Cameron had led calls for the resignation of Brooks amid public outrage over allegations that the News of the World hacked the voicemails of murdered teenager Milly Dowler and of the families of dead soldiers.

It ends a meteoric rise, having started as a secretary at the News of World at the age of 20, before she became editor from 2000-2003 and then going on to edit The Sun until 2009.

"As Chief Executive of the company, I feel a deep sense of responsibility for the people we have hurt and I want to reiterate how sorry I am for what we now know to have taken place," Brooks wrote.

"I have believed that the right and responsible action has been to lead us through the heat of the crisis. However my desire to remain on the bridge has made me a focal point of the debate."

In the United States, the Federal Bureau of Investigation announced that News Corp. employees may have targeted the phone records of victims of the September 11 attacks.

"We are aware of the allegations and we are looking into it," a spokeswoman from the FBI's New York office told AFP.

The FBI inquiries are preliminary in nature and do not constitute a formal investigation but US Attorney-General Eric Holder said on Friday that his office was reviewing requests from congressmen for a probe into News Corp.

"There have been serious allegations raised in that regard in Great Britain and there is an ongoing investigation there," Holder told reporters in Sydney, where he is attending a meeting of justice officials.

But in an interview with his flagship US newspaper, The Wall Street Journal, Murdoch insisted the crisis was being handled "extremely well in every way possible" and angrily denounced criticism made by British MPs as "lies".

Murdoch also said an independent committee led by a "distinguished non-employee" would probe every charge of misconduct made against News Corp.

Murdoch and his son James, the chairman of News International and deputy chief operating officer of News Corp., had both initially resisted being called before a committee of British MPs.

But Murdoch told the Journal he wanted to address "some of the things that have been said in parliament, some of which are total lies."

Nine people have been arrested over the scandal so far. The latest was Neil Wallis, a former deputy editor of the News of the World and editor of another tabloid, the Sunday Mirror.

Wallis, 60, had been deputy to Andy Coulson who later went on to become the communications chief to Prime Minister David Cameron.

As well as embarrassing Cameron, the scandal has also embroiled the police with the revelation that Wallis had been hired by Scotland Yard Chief Paul Stephenson, prompting calls on Friday for the commissioner to quit.