As the Metropolitan Police says it will consider new evidence about allegations of widespread phone hacking by the News of the World, we look at some key questions surrounding the story.
What is the row about?
The story goes back to 2007 when the News of the World's royal editor, Clive Goodman, was jailed for conspiracy to access phone messages left for royal aides.
Goodman, along with private investigator Glenn Mulcaire, who was jailed for six months for the same charge, used mobile phone numbers and secret codes used by network operators to hack into the voicemails to see if there was any information of interest.
The pair targeted the Prince of Wales, Prince William and Prince Harry.
A court heard that Mulcaire had also hacked into the messages of supermodel Elle Macpherson.
The paper's editor Andy Coulson later resigned, saying he took responsibility for the scandal, and the News of the World said it was a one-off case.
What happened next?
In 2009 the Guardian claimed News of the World journalists were involved in widespread phone hacking of several thousand celebrities, sports stars and politicians.
On the Guardian's list were former Deputy Prime Minister Lord Prescott, former Culture Secretary Tessa Jowell, celebrity cook Nigella Lawson, actress Gwyneth Paltrow, London Mayor Boris Johnson, comedian Lenny Henry, singer George Michael and the late Jade Goody.
The paper said it had evidence that News Group Newspapers - owner of the title - paid £1m to settle legal cases that might have revealed evidence of illegal activities.
News Group were accused by the paper of persuading the court to "seal the file" to prevent all public access.
If that evidence had been made available, the victims of phone hacking may have been able to take action against the Sunday newspaper.
Was there any action taken?
Assistant Met Police Commissioner John Yates was ordered to "establish the facts" as calls grew for a police inquiry.
Mr Yates decided "no further investigation" would be conducted into the allegations.
He said where there was evidence that people had been the subject of any form of phone tapping, they had been informed, but the numbers were much, much lower than those reported.
And after investigating, the Press Complaints Commission (PCC) watchdog said it had found "no evidence" that phone-message tapping was still going on.
While critical of the conduct of the News of the World's journalists, the House of Commons Culture and Media Committee found no evidence that Mr Coulson either approved phone-hacking by his paper, or was aware it was taking place.
However in February of this year, the Culture, Media and Sport committee interviewed News International bosses over the Guardian's accusations and decided there had been more than a handful of victims and it was inconceivable no-one at the tabloid had known.
The cross-party parliamentary committee criticised the Press Complaints Commission for not investigating the case properly and called for the watchdog to be given greater powers to help improve its credibility and authority.
Why has the row been reignited?
A New York Times story, published last week, suggested the practice of phone hacking was widespread at the newspaper.
Former News of the World employee Sean Hoare, one of the sources for the New York Times' allegations, told the BBC that phone tapping was "endemic" within the industry and he had been personally "requested" to do it by his then editor, Mr Coulson.
Mr Coulson has denied he knew anything about the phone tapping and has offered to speak to the police about the allegations.
The New York Times story has prompted Labour politicians to call for action to be taken and the Metropolitan Police says it will now reopen the investigation.
Where does this leave News Group?
If a full list of names were to be published, it could pave the way for further claims over breach of privacy against the newspaper owners.
The News of the World said the New York Times story "contained no new evidence".
"It relies on unsubstantiated allegations from unnamed sources or claims from disgruntled former employees that should be treated with extreme scepticism given the reasons for departures from this newspaper," it said in a statement.
"We reject absolutely any suggestion there was widespread culture of wrongdoing at the News of the World."
What have the police done?
In 2009, the Metropolitan Police chose not to launch an investigation following the Guardian's claims.
But following the New York Times story, and the claims made by Mr Hoare to the BBC, the police have said they will reopen the investigation.
Assistant Commissioner John Yates told BBC Radio 4's Today programme: "We've always said that if any new material or new evidence was produced then we would consider it.
"We've heard what Mr Hoare's had to say, we've been in touch with the New York Times for many months prior to the publication of the article, seeking any new material or new evidence that they had. They didn't produce any until they published this with Mr Hoare.
"It is new and we'll be considering it, and consulting with the Crown Prosecution Service before we do."
Culture committee chairman John Whittingdale told the BBC he was against MPs reopening their inquiry into the claims.
He said the committee's previous investigation was as detailed as it could be at the time and it stood by its conclusions.
Why does it matter?
Andy Coulson was News of the World editor when his journalists were allegedly involved in the phone hacking operation three or four years ago. Now he is director of communications for the Conservative Party.
He started his journalism career on regional papers, rising rapidly to become News of the World editor by his mid-30s.
He oversaw a string of tabloid exclusives but resigned in January 2007 on the day his royal editor Clive Goodman was jailed for four months for illegal phone hacking; Mr Coulson denied having had any knowledge of his activities.
Less than six months later, David Cameron had hired him.
Labour leadership contender Ed Balls, former Labour minister Tessa Jowell, who says her phone was hacked 28 times, and former Deputy Prime Minister Lord Prescott, who also believes he was targeted, have all called for action.
Mr Balls said Mr Coulson's role at the heart of Number 10 meant that the government's "integrity" was under question.
What have the Tories said?
Mr Coulson has received strong backing from No 10 which says he "totally and utterly" rejects claims he was aware of any wrongdoing. It said Mr Coulson stood by his evidence to the Culture Committee last year.
And Education Secretary Michael Gove told the BBC there seemed to be "a recycling of allegations" and claimed "there is an element of the party political" about the reaction by some Labour politicians to the claims.
"The police have looked at these allegations and decided there is no case to answer," he said.
How can a mobile phone be hacked into?
Security experts says there are three methods of intercepting mobile calls: at the handset; during the conversation - which is illegal and very expensive - or through the mobile phone company which connects the device.
Are there laws preventing people from hacking into phones?
It is illegal to gain access to another person's telephone under Section 1 of the Regulation of Investigatory Powers Act 2000 (RIPA).
Legal affairs analyst Jon Silverman said the only exception is if the hacking is being done by the authorities, who will have gained legal clearance.
What are the penalties for breaking the law in this way?
The maximum sentence is two years in prison, or a fine, or possibly both.