Mark Lewis, the lawyer who has been at the forefront of efforts to expose the News of the World phone-hacking scandal, is poised to bring the battle for legal redress across the Atlantic and to the doorstep of Rupert Murdoch's media empire.

Lewis will arrive in the US on Saturday and next week will begin legal discussions in New York, just a stone's throw away from News Corporation's global headquarters on Sixth Avenue. His arrival constitutes a major escalation in the legal ramifications of the hacking scandal for Murdoch, who has tried desperately to keep it away from the American core of his multi-billion-dollar media holdings.

Details remain sketchy about precisely what Lewis intends to do in the US, but the Guardian has learned that he will be having legal discussions that could lead to several lawsuits being lodged with the New York courts. The direct involvement of the US judicial system in allegations of illegal activity by News Corp employees would bring the scandal dramatically closer to Murdoch's adopted home.

It is not yet known how many lawsuits could result. Lewis will be in discussions with his New York-based legal partner, Norman Siegel, former director of the New York Civil Liberties Union, over the details of US law as it applies to phone hacking.

The cases they will be exploring are understood to relate mainly to celebrities who have come to the US and had their phones hacked while they were in the country. That could constitute a violation of US telecommunications and privacy laws.

It is also understood that a US citizen had his or her phone hacked while in America as a result of hacking into the transatlantic conversation of a foreign-based celebrity who was a friend of the victim.

Jude Law has been one of the celebrities believed to have their phones hacked while in the US, in this case while he was at JFK airport in New York. However, the Guardian understands that Law is not one of the cases that is currently being explored by Lewis and Siegel.

So far, the US component of the hacking scandal has been confined to an FBI and department of justice investigation under the Foreign Corrupt Practices Act that forbids corporations headquartered in the US, as News Corporation is, from indulging in acts of bribery or corruption abroad. Any lawsuit that flows from Lewis's US activities would take the scandal to another level by becoming the first legal action to arise domestically within the US.

Lewis has been a crucial figure in the exposure of the billowing phone-hacking saga. He represents the family of Milly Dowler, the missing teenager whose phone was hacked by the News of the World.

He also represented Gordon Taylor, head of the Professional Footballers' Association, who received more than $1m from News International, the UK newspaper arm of News Corporation, in a settlement over the hacking of his phone.

Lewis's involvement with the scandal has also been deeply personal: he was himself put under surveillance by the News of the World before it was shut down by Murdoch. The paper hired a specialist private investigator to covertly surveil him and his family.

Lewis will be attending a symposium on investigative journalism at UC Berkeley this weekend where he will be speaking on a panel titled: "The Murdoch Effect: The News At Any Price?"

An irony of the arrival of Lewis in the US is that it comes soon after James Murdoch, Rupert's youngest son, relocated from the UK to New York partially, it is thought, in a move to try and distance him from the phone-hacking scandal. James Murdoch announced that he was stepping down as nonexecutive chairman of the broadcaster BskyB last week, but Lewis's deliberations over possible legal action in the New York courts brings the nightmare back to haunt him.