Relatives of soldiers killed in Iraq and Afghanistan may have been victims of News of the World phone hacking, it has emerged.
News International, the newspaper's publisher, said it would be "absolutely appalled and horrified" if there was any truth to the claims.
The latest allegations came after Prime Minister David Cameron ordered a public inquiry into the scandal and Rupert Murdoch said phone hacking at one of his flagship newspapers was "deplorable and unacceptable".
MPH Solicitors - whose clients include Samantha Roberts, widow of Sgt Steven Roberts, the first British soldier killed in combat in Iraq in 2003 - called for clarity from authorities over the claims.
Solicitor Geraldine McCool said the firm had been contacted by press yesterday over the allegations surrounding high-profile military inquests in 2006 and 2007.
Ms McCool, a senior lawyer who represented Mrs Roberts, said there was no evidence to show confidential information was obtained through hacking.
She added: "I sincerely hope that any future revelations do not involve our clients and that full disclosure of the extent of this diabolical practice is now made."
And a lawyer for Rose Gentle, whose son Fusilier Gordon Gentle was killed in Iraq in 2004, said he had contacted police to find out if the phones of Ms Gentle and other families were targeted.
Steven Heffer, of Collyer Bristow Solicitors, said: "It is imperative that the families get to the bottom of this issue very quickly as any delay only adds to their grief and suffering. I am hoping the police will deal with their requests for information quickly and sympathetically."
In response to the latest claims, a News International spokesman said: "News International's record as a friend of the armed services and of our servicemen and servicewomen is impeccable.
"Our titles have campaigned in support of the military over many years and will continue to do so. If these allegations are true we are absolutely appalled and horrified. We will be contacting the MoD immediately to try and verify the situation."
A spokesman for the MoD, which is understood to be working closely with Scotland Yard on the issue, said: "This is a matter for the Metropolitan Police who are investigating these allegations. It would be inappropriate for us to comment whilst this investigation is ongoing."
The most recent allegations came after Rupert Murdoch, chairman and chief executive of News International's parent company, News Corporation, branded claims of phone hacking at the paper "deplorable and unacceptable".
He backed Rebekah Brooks to continue as chief executive of News International however, despite claims the tabloid hacked murdered schoolgirl Milly Dowler's phone while she was editor.
In a statement yesterday Mr Murdoch said: "Recent allegations of phone hacking and making payments to police with respect to the News of the World are deplorable and unacceptable.
"I have made clear that our company must fully and proactively co-operate with the police in all investigations and that is exactly what News International has been doing and will continue to do under Rebekah Brooks' leadership.
"We are committed to addressing these issues fully and have taken a number of important steps to prevent them from happening again."
It has also emerged that George Osborne's private home phone number appeared in records kept by the two men at the centre of the original hacking furore.
The Chancellor's name and details were discovered among the thousands of pages of notes kept by private investigator Glenn Mulcaire and former NoTW royal editor Clive Goodman, his spokesman said.
The pair were jailed in 2007 after plotting to intercept voicemail messages left for royal aides.
There is no suggestion the Chancellor's phone was hacked by the men, the spokesman stressed.
Families of 7/7 bombing victims and the parents of murdered Soham schoolgirls Holly Wells and Jessica Chapman have also been told by police they may have been targeted.
Political and commercial pressure has mounted on News International as more companies pulled advertising from the paper and MPs, including Labour leader Ed Miliband, said Ms Brooks had to go.
Halifax and the Co-operative Group joined Ford, Vauxhall, Mitsubishi, Butlins and Virgin Holidays in suspending their marketing.
MPs used a three-hour emergency Commons debate yesterday on the revelations to condemn journalistic practices at the NoTW.
Labour MP Tom Watson even demanded the suspension of James Murdoch, Mr Murdoch's son and the chairman of News International.
In the Commons he alleged that James Murdoch attempted to pervert the course of justice.
He said: "It is clear now that he personally, without board approval, authorised money to be paid by his company to silence people who had been hacked and to cover up criminal behaviour within his organisation."
Mr Cameron told MPs at Prime Minister's questions that he supported holding one or more inquiries into the scandal.
Mr Cameron said there were two "vital areas" that needed to be considered - why the original police inquiry into News of the World phone hacking failed to get to the bottom of what happened, as well as the behaviour, practices and ethics of journalists and media organisations.
In an email to Liberal Democrat MPs last night, Mr Clegg said: "The PM and I have agreed that there will be inquiries into both the original police investigation and also the behaviour of the British press, their practices and ethics - and that the details of those inquiries will be agreed by the party leaders.
"On your behalf I will be making it clear that the inquiries must be independent, open, able to access all information and call witnesses, and that crucially the inquiry dealing with legal issues (eg relationship between police and media) must be presided over by a judge."
News International executives said they were "very close" to discovering who commissioned Mulcaire to allegedly hack Milly's phone after she went missing in 2002.
Simon Greenberg, the company's director of corporate affairs, said he was "clear" that the individual was not Ms Brooks.
The Times, which is owned by News International, today claimed that five journalists and newspaper executives suspected of involvement in the scandal were expected to be arrested within days.
The scandal hit shares yesterday in BSkyB, which fell 18p to 827p on the London market, as concerns grew over the possible impact it could have on News Corporation's bid for the satellite broadcaster.
And in the US last night, News Corporation was among the biggest losers on Wall Street's Dow Jones index, falling 3.6%.