British Prime Minister David Cameron has given his backing to a police enquiry into the phone hacking scandal at Rupert Murdoch's News International.
The hacking, which has prompted national outrage, will also be debated later today in the British parliament as pressure mounts on Rebekah Brooks, the embattled chief executive of the company, to step down.
"We do need to have an inquiry, possibly inquiries, into what has happened," Mr Cameron told parliament.
People had been "revolted" by the affair, in which journalists were said to have tapped into the mobile phone of abducted girl Milly Dowler who was later found to have been murdered.
The government has been under increasing pressure to hold an inquiry after allegations of phone hacking against the top-selling tabloid News of the World spread beyond politicians and celebrities to victims of crime.
Ms Brooks, while editor of NOTW, used Steve Whittamore, a private detective who specialised in obtaining illegal information, to "convert" a mobile phone number to find its registered owner. Mr Whittamore also provided the paper with the Dowlers' ex-directory home phone number.
The British Information Commissioner's Office, which successfully prosecuted Whittamore for breaches of the Data Protection Act in 2005, said last night it would have been illegal to obtain the mobile conversion if the details had been "blagged" from a phone company, according to the London Independent.
Ms Brooks, who said yesterday she was "shocked and appalled" at the latest hacking claims, admitted requesting the information. But she said it could be obtained by "perfectly legitimate means". She faced demands for her resignation last night.
The revelation came as News International battled a political and commercial firestorm over the disclosure that its bestselling paper interfered with the police investigation into Milly's disappearance in March 2002 by hacking into her mobile phone and deleting messages. One big advertiser, Ford, announced it was suspending its account with the paper while the energy company Npower and Halifax bank said they were considering options. Thousands of readers joined boycott campaigns on Facebook and Twitter.
An emergency three-hour debate is to be held in the British House of Commons today. The Labour leader Ed Miliband hardened his position on the scandal, demanding a public inquiry and calling for Ms Brooks to "consider her conscience and consider her position".
Responding to growing clamour for her to step down, Ms Brooks yesterday told News International staff it was "inconceivable" that she knew of or sanctioned the hacking of Milly's mobile phone. In a passionate defence of her position, she wrote: "I have to tell you that I am sickened that these events are alleged to have happened. Not just because I was editor of the News of the World at the time, but if the accusations are true, the devastating effect on Milly Dowler's family is unforgivable."
No evidence has been presented that Ms Brooks was aware of Mulcaire's activities surrounding Milly's disappearance. But an investigation by The Independent shows she was aware of the existence of Whittamore, who used an associate to obtain the Dowlers' home phone number from BT, and made use of his services in an unrelated case.
A copy of the "Blue Book" obtained by The Independent, which covers more than 1,000 transactions carried out for New International's titles between 2000 and 2003, records a request in 2001 from Ms Brooks (whose surname was then Wade) for a "mobile conversion" along with a mobile phone number. She made a second request for an electoral roll search for an address in Doncaster, South Yorkshire. The address was occupied at the time by a painter-decorator who lived in a flat above a bike shop in the town.
A friend said: "I have no idea why the editor of the News of the World would have been interested in him. He's just an ordinary guy."
When asked last year by MPs to explain the circumstances around her request, Ms Brooks said she could no longer remember why she wanted to convert the number.
"This was nine years ago and I cannot recall why I required this particular conversion," she wrote.
"You should note that 'conversion'... is often carried out through perfectly legitimate means such as a web search."
A spokeswoman for the British Information Commission Office said: "If that information was obtained by 'blagging' then it would have been illegal under Section 55 of the Data Protection Act."
Rebekah Brooks, the embattled chief executive of Rupert Murdoch's News International, personally commissioned searches by one of the private investigators who was later used by the News of the World to trace the family of the murdered Surrey schoolgirl Milly Dowler, it emerged today.