Here is the full internal message from Rebekah Brooks to News International staff:
"At News International we pride ourselves on setting the news agenda for the right reasons. Today we are leading the news for the wrong ones.
"The reputation of the company we love so much, as well as the press freedoms we value so highly, are all at risk.
"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.
"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.
"Therefore I have given Rupert and James Murdoch my resignation.
"While it has been a subject of discussion, this time my resignation has been accepted.
"Rupert's wisdom, kindness and incisive advice has guided me throughout my career and James is an inspirational leader who has shown me great loyalty and friendship.
"I would like to thank them both for their support.
"I have worked here for 22 years and I know it to be part of the finest media company in the world.
"News International is full of talented, professional and honourable people. I am proud to have been part of the team and lucky to know so many brilliant journalists and media executives.
"I leave with the happiest of memories and an abundance of friends.
"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 cooperation 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.
"I wish every one of you all the best."
Following Ms Brooks' resignation, News International named Tom Mockridge as her successor.
Here is the full statement announcing his appointment:
"News Corporation today announced the appointment of Tom Mockridge to the role of Chief Executive Officer of News International.
"Mr Mockridge will assume responsibility for his new role with immediate effect following the resignation of Rebekah Brooks.
"Mr Mockridge joins News International from Sky Italia where he has been Chief Executive Officer since launch in 2003. He was also Chief Executive European Television of News Corporation, overseeing News Corporation's television operations in Europe, outside of the UK.
"Laura Cioli, Chief Operating Officer, and Domenico Labianca, Chief Finance Officer, will assume Mr Mockridge's responsibilities on an interim basis, reporting to James Murdoch, Deputy Chief Operating Officer and Chairman and CEO, International, News Corporation.
"Prior to joining Sky Italia, Mr Mockridge was Chief Executive of the publicly-listed New Zealand company, Independent Newspapers, and Chairman of Sky New Zealand.
"He previously held various roles at Star Group Limited and spent three years as Chief Executive Officer of Foxtel, News Corporation's Australian pay TV joint venture.
"Mr Mockridge joined News Corporation in January 1991, working for Ken Cowley, Chairman and Chief Executive of the Australian newspaper company News Limited.
"Before that, he was a spokesperson in the Australian government. He started his career as a newspaper journalist in New Zealand.
Mr Mockridge is also a non-executive director of BSkyB and a member of the Supervisory Board of Sky Deutschland.
"James Murdoch, Deputy Chief Operating Officer and Chairman and CEO, International, News Corporation, said: 'Tom is an outstanding executive with unrivalled experience across our journalism and television businesses.
"He has proven himself to be a very effective operator in his time at Sky Italia.
"Under his leadership, Sky has grown to become one of the world's most successful pay TV businesses, reaching close to 5 million homes and launching channels like TG24 which has set a new standard for independent journalism in Italy.
"I believe that Tom is the best person to move the company forward to a brighter future."
News Corporation's chief executive in Europe James Murdoch sent the following message to News International staff:
"I am writing to update you on the actions we have been taking as a company to solve the problems at News International relating to the News of the World, in addition to continuing to co-operate fully and actively with the police and settling civil claims.
:: Earlier today, Rebekah Brooks resigned from her position as CEO. I understand her decision and I want to thank her for her 22 years of service to the company. She has been one of the outstanding editors of her generation and she can be proud of many accomplishments as an executive. We support her as she takes this step to clear her name;
:: We have created an independent Management & Standards Committee and I want to emphasise its importance. The Committee has direct governance and oversight from News Corporation Board members and is codifying standards that will be clear and enforced;
:: We made the difficult and necessary decision to close the News of the World;
:: A number of other executives have now left the company;
:: News Corporation also withdrew its proposal to acquire the shares in BSkyB it does not own. This is a strong signal that our top priority in the UK is to address the issues facing News International.
Looking to the future, I am also pleased to tell you that Tom Mockridge will become CEO of News International. Tom is 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. 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. The creation of TG-24, Italy's only truly independent 24 hours news channel, is a credit to Tom's leadership and integrity.
This weekend, News International will run advertisements in all national newspapers. 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.
Next week, my father and I will appear before the CMS Select Committee and will speak to them directly about our determination to put things right.
The company has made mistakes. It is not only receiving appropriate scrutiny, but is also responding to unfair attacks by setting the record straight.
I would like to conclude by saying thank you. Throughout this time, you have gotten out great papers every day and have stayed focused. I am deeply grateful for that."