The Metropolitan Police is facing intense pressure to reopen its investigation into illegal phone hacking by journalists amid claims that Gordon Brown may have been among the victims.
Senior politicians from both Government and opposition have combined to demand that police investigate fully the latest allegations that the mobile phones of prominent public figures had been targeted.
Labour deputy leader Harriet Harman said the law must be enforced, while the Lib Dem Energy Secretary Chris Huhne said it was "implausible" to claim the practice was confined to "one rogue reporter" at the News of the World.
Their comments came as it emerged that Brown had written to Scotland Yard over the summer expressing concern that his voicemail messages may have been broken into.
The former prime minister is the most senior public figure to be drawn into the controversy, which last week saw Andy Coulson resign as David Cameron's director of communications amid continuing allegations of phone hacking by reporters at the News of the World when he was editor of the paper.
Brown's office would not comment on the reports, while Scotland Yard also declined to respond to the latest allegations. However Harman said that if the law had been broken "it should be investigated by the police and it should be enforced".
Huhne said that it was clear that the practice extended far beyond the News of the World's former royal correspondent Clive Goodman, who was jailed in 2007 along with private investigator Glenn Mulcaire.
He said that the Metropolitan Police Commissioner Sir Paul Stephenson needed to ensure that the issue was "really dealt with".
Scotland Yard formally closed its investigation into the allegations against the News of the World last month.
However a number of public figures are continuing to pursue civil legal actions against both the newspaper and the police, prompting a series of fresh disclosures.
Earlier this month, the Met announced that it was passing all its evidence to the Director of Public Prosecutions Keir Starmer for lawyers at the CPS to review.
There has been growing criticism - particularly among senior Labour figures - at the apparent reluctance of the police to pursue the case more vigorously.
Tony Blair's former communication chief Alastair Campbell described the Met's handling of the case as "extraordinary" and a "scandal".
A leading media lawyer claimed over the weekend that the phone-hacking allegations were not just confined to one newspaper.
Mark Lewis, who acted for Gordon Taylor of the Professional Footballers' Association in a damages claim against the News of the World, said he was representing four people who believe they were targeted by other newspapers.
Jenny Jones, a Green Party member of the Metropolitan Police Authority, admitted she had lost some faith in the Met.
Speaking on BBC Radio 5 Live, she said: "I have a lack of confidence with several issues and this case is one of them."
The force's reputation had suffered, she said, and it could not afford for there to be too many cases like this one.
But she defended the Met's relationship with the press, pointing out that a large volume of resources would be needed to conduct an investigation into the affair.
"It's a very expensive process to carry on with lots and lots of emails and would need lots of experienced, highly trained officers," she said.
And it was important that the Met "sometimes" had a good relationship with the press, she stressed, with each side feeding information to the other.
"At its best a relationship can be extremely useful but at its worst obviously then we're moving into a completely different area," she added.