Rebekah Brooks, the News International chief executive, has resigned after 11 days of mounting political pressure over the phone-hacking scandal.

Brooks announced her decision to News International staff in Wapping just before 10am on Friday, saying her resignation had been accepted by Rupert and James Murdoch. She said she no longer wanted to be a "focal point of the debate" surrounding the company's future and reputation.

She stopped short of issuing a personal apology. "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 said in a statement.

"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.

"This is now detracting attention from all our honest endeavours to fix the problems of the past."

Brooks praised Rupert and James Murdoch and said she leaves "with the happiest memories and an abundance of friends".

Brooks is to be replaced by the chief executive of Sky Italia, Tom Mockridge, who will take over at Wapping immediately.

It is not yet clear exactly why Brooks's resignation after 22 years at the company was accepted by the Murdochs, who had so far steadfastly stood by her during the crisis. This despite calls for her to go from the leaders of all the main political parties, including the prime minister, David Cameron, and the family of murdered schoolgirl Milly Dowler, whose mobile phone was allegedly hacked by a private investigator working for the News of the World.

However, the last straw may have been Thursday night's Newsnight interview with News International parent company News Corporation's second largest shareholder, Saudi prince Al-Waleed bin Talal Alsaud, in which he said that if there was evidence of Brooks's "explicit" involvement in the alleged illegal activity, "for sure she has to go, you bet she has to go".

Brooks also faced an uncomfortable appearance before MPs on the Commons culture, media and sport select committee on Tuesday along with Rupert and James Murdoch to answer questions about the phone-hacking scandal. In her resignation statement she indicated that she would still appear before the committee.

In her statement Brooks said she wanted to clear her name as well as the company's. "The reputation of the company we love so much, as well as the press freedoms we value so highly, are all at risk," she added.

"As you can imagine recent times have been tough. I now need to concentrate on correcting the distortions and rebutting the allegations about my record as a journalist, an editor and executive.

"My resignation makes it possible for me to have the freedom and the time to give my full co-operation to all the current and future inquiries, the police investigations and the CMS appearance. I am so grateful for all the messages of support. I have nothing but overwhelming respect for you and our millions of readers."

James Murdoch, who has management responsibility for News International as News Corp's deputy chief operating officer, said in a memo to Wapping staff that Brooks had been "one of the outstanding editors of her generation" who could be "proud of many accomplishments as an executive". "We support her as she takes this step to clear her name," he added.

Murdoch welcomed the appointment of Mockridge as Brooks's successor, saying he was "in London today and will start right away".

"Tom is a highly respected and accomplished media executive who has served as CEO of Sky Italia since its launch in 2003," he added. "Tom, who has also been in charge of our European television business, started his career as a newspaper journalist in New Zealand and he has held a range of top roles in the newspaper industry."

Murdoch also confirmed that News International would run full-page ads in the national press at the weekend apologising for the phone-hacking scandal, as reported by the Guardian on Thursday.

"We will apologise to the nation for what has happened. We will follow this up in the future with communications about the actions we have taken to address the wrongdoing that occurred. We are also sending letters to our commercial partners with an update on the actions we are taking," he said.

"The company has made mistakes. It is not only receiving appropriate scrutiny, but is also responding to unfair attacks by setting the record straight."

Alsaud, known as the "Arab Warren Buffet" and the nephew of the Saudi king, also told Newsnight: "If the indications are that her involvement in this matter is explicit ... for sure she has to go, you bet she has to go. Ethics to me is very important. I will not tolerate to deal with a company that has a lady or a man that has any sliver of doubts on her or his integrity. From my dealings with Mr James Murdoch and Rupert Murdoch it's almost impossible for James and Rupert to know what's going on at News of the World level.

"The problems have been at the News of the World newspaper and not at News Corp level. I'd like to differentiate between News Corporation conglomerate and the News of the World that got shut down. These tactics used by tabloid newspapers in the UK were done not only by News of the World but by other tabloid newspapers also.

"I hope that this matter doesn't get over-politicised. Clearly some politicians in the UK and US right now would like to set the record clear and take revenge on Mr Murdoch's conglomerate that wasn't really on their side some time ago."

Pressure has intensified on 43-year-old Brooks to stand down since the hacking scandal re-erupted following the Guardian's disclosure on 4 July that private investigator Glenn Mulcaire, working for the News of the World, allegedly hacked into Dowler's mobile phone between her disappearance and the discovery of her body in 2002.

The public revulsion over the revelation and subsequent allegations that the families of British soldiers killed in Afghanistan and Iraq and the victims of the 7/7 terrorist attacks may have been targeted led to the decision last week by News Corporation to close the News of the World.

However, as the scandal snowballed Brooks stood firm and showed no sign of buckling under the pressure. She told News International staff that it was "inconceivable" that she knew about the hacking of Dowler's phone.

Brooks also faced down the anger of News of the World staff in two separate meetings with them last week amid claims that their paper and their jobs were being sacrificed to save her.

She also appeared to have been protected by Rupert Murdoch, who is said to fondly regard her almost as a fifth daughter.

Until Friday morning's announcement, this support even appeared to withstand cross-party calls for her to step down. She had also been cast adrift by Cameron, formerly part of the same Oxfordshire social circle. He said last week: "It has been reported that she offered her resignation over this and in this situation I would have taken it."

This time it has. Cameron's official spokesman said today her resignation was "the right decision".

The Labour leader, Ed Miliband, had described Brooks's ongoing employment at News International as an "insult" to the Dowler family. He wrote today on Twitter: "It is right that Rebekah Brooks has finally taken responsibility and resigned" and called on Rupert Murdoch to apologise to the Dowlers.

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