A key US senator called for a probe into whether alleged hacking by Rupert Murdoch's media empire had extended to US citizens and warned of "severe" consequences if that proved the case.
"I encourage the appropriate agencies to investigate to ensure that Americans have not had their privacy violated," senate commerce committee chairman Jay Rockefeller said in a statement.
"I am concerned that the admitted phone hacking in London by the News Corp may have extended to 9/11 victims or other Americans. If they did, the consequences will be severe," said Rockefeller, a Democrat.
His comments came as Murdoch faced an onslaught from British MPs as the government backed calls for him to drop his bid for pay TV giant BSkyB and a committee summoned him to answer questions on phone hacking.
Former prime minister Gordon Brown also piled pressure on Murdoch's media empire, accusing it of hiring "criminals" to obtain his private documents and suggesting it used illegal methods to break the news of his son's illness.
Scotland Yard added to the 80-year-old tycoon's woes, accusing his newspapers of blocking their investigations into hacking at the News of the World, the beleaguered tabloid that Murdoch axed on Sunday.
"The reported hacking by News Corporation newspapers against a range of individuals-including children-is offensive and a serious breach of journalistic ethics. This raises serious questions about whether the company has broken US law," said Rockefeller.
The legislator, who chaired the US senate's intelligence committee for years, was the first major voice in the US congress to call for an investigation into the scandal, which has captivated Britain.