Questions have been raised over whether the phone messages of soldiers' families were hacked by the News of the World.
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".
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.
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 journalists yesterday over the allegations surrounding high-profile military inquests in 2006 and 2007.
McCool, a senior lawyer who represented 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 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."
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.
Political pressure mounts
It also emerged yesterday that Chancellor George Osborne'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."
Cameron told MPs at Prime Minister's questions that he supported holding one or more inquiries into the scandal.
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, Deputy Prime Minister Nick 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 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.
Met officers 'received up to £30,000'
Meanwhile, former Scotland Yard deputy assistant commissioner Brian Paddick said he understood that News International was handing over details about a handful of corrupt police officers who had been paid in exchange for tip-offs about stories.
He told BBC Breakfast that some officers had received up to £30,000 for giving information to journalists.
Paddick said: "Now there are apparently emails being passed to the police by News International giving information about which officers were being paid.
"My understanding is that News International are now co-operating with the police in a handful of cases in terms of officers who may have received payments.
"It is a criminal offence - it is police corruption.
"It goes all the way from tipping off the press that George Michael had been arrested for driving into Snappy Snaps through to jeopardising serious criminal investigations by giving out confidential information that could be useful to criminals."
He continued: "Rebecca Brooks had told the House of Commons committee back in 2003 that they were paying police officers for information.
"Yesterday I met a journalist who said he was paying sometimes £20,000 to £30,000 to police officers for information.
"All of this is done in a very clandestine way. You know the stories about a drive-through fast food restaurant near the News International headquarters, that's where police officers used to go to collect envelopes. It was all done very discreetly. I personally never came across it during my career."
He added that a judge-led inquiry needed to be conducted into the allegations so witnesses could be compelled to give evidence on oath.
Sara Payne denies phone-hack allegations
Sara Payne, the mother of murdered schoolgirl Sarah Payne, denied suggestions that she may have had her phone hacked, saying she has not been contacted by police.
She said: "First, my thoughts go to all those affected.
"Second, there has been a great deal of speculation over the last few days, in the papers and in Parliament, regarding allegations that my phone may have been hacked.
"To be clear, I have not been contacted by the police and I have not been shown any evidence that I have been a victim of phone hacking.
"If I was shown any evidence, I would deal with the matter immediately and with the appropriate authorities.
"If what is alleged is true, it is an intolerable abuse and when the time is right, as a victims' advocate, I will challenge the News of the World team myself and help them to develop a better way ahead.
"In the meantime, we must respect the system process and wait to see what goes from allegation to established fact."