Mark Lewis, the UK lawyer who has represented various alleged victims of phone hacking, has revealed that he and US legal partner Norman Siegel have been approached by at least ten people with complaints relating to News Corp.
Lewis has already confirmed that he is looking to launch legal action on behalf of three people in relation to alleged hacking by News of the World journalists into phones on US soil.
Crucially, though, the lawyer said that the complaints also extend to other News Corp holdings, such as Fox News, reports The Guardian.
Lewis said that he had been contacted by people in the US "raising issues against other [News Corp] titles or Fox News, not necessarily about hacking but about other untoward dark arts to obtain information that should be private".
He stressed, though, that the allegations were unproven.
Lewis also confirmed that he has taken on a fourth case of alleged phone hacking in the US. This is in addition to the existing three, of which one is known to be an American citizen and the other two are Europeans, who all believe their phones were hacked while in the US.
He added that there was "substantial and substantiated" evidence relating to the notes of Glenn Mulcaire, the private investigator jailed for phone hacking on behalf of the News of the World, that indicated illegal hacking of phones on US soil between 2001 and 2006.
At a meeting in New York, Siegel also said that he had been contacted by six individuals regarding complaints against News Corp subsidiaries.
"My experience in these sorts of cases is that when people sense you are serious and balanced in your approach, they begin to come out of the woodwork," he said.
News Corp said that it had "no comment" on the visit of Lewis to the US, but the prospect of legal action in America, where the company is based, will no doubt be taken very seriously. Federal law is very stringent against alleged hacking of an individual's communications.
This week, News Corp announced that it will strip all foreign holders of its B shares of half their voting rights with immediate effect in order for it to avoid breaking foreign ownership limits on holders of US broadcasting licences.
Rupert Murdoch said that he and his family trust will cap their voting rights at 39.7%, even if they purchase more shares, but the move will reduce the power of Prince Al Waleed bin Talal, the second largest holder of News Corp's voting B shares, who will see his voting rights cut from about 7% to 3.5%.
The company said that it was making the move to comply with US law, which states that non-US shareholders cannot control more than 25% of any company holding broadcasting licences.
After News Corp started the process of renewing its licences, including Fox's, the company found that foreign owners held around 36% of class B shares, and so it has moved to suspend 50% of their voting rights "for as long as the company deems it necessary to maintain compliance with US law".
However, the move is also being viewed as News Corp removing any reason that regulators could use to strip away its valuable broadcasting licences should legal scandals spread to the US.
In the UK, where News Corp's News International publisher has faced and is still facing various legal cases over hacking, Ofcom has warned that it could look to revoke the broadcasting licence of Sky if News Corp, which owns 39.1% of the pay-TV giant, was found not to be "fit and proper" to retain the stake.
"James Murdoch is now in the US rather than in England, and we have to look at that," Lewis said at the meeting. "It becomes relevant to all sorts of issues in respect to knowledge in terms of punitive damages."
Discussing whether Rupert Murdoch could be unseated as chairman and chief executive of News Corp, the lawyer replied: "You go wherever the evidence takes you. We don't rule anything in or out."
Meanwhile, the Murdochs have been called to give evidence in person at the Leveson inquiry into press standards and ethics in London next week.
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