Rupert Murdoch's global empire is set to face new legal action in the US over alleged illegal practices by News Corp journalists. The lawyer at the heart of the phone-hacking scandal in the UK, Mark Lewis, who was instrumental in exposing the scale of illegal voicemail accessing at the News of the World, is in the "advanced stages" of bringing his first case against News Corp on the other side of the Atlantic.

The news comes as Mr Murdoch prepares to fly to London following a series of arrests of senior Sun journalists.

The prospect of Mr Lewis supervising legal action in the US will do little to reassure the embattled board of News Corp that a new front on illegal practices is about to open in their own back yard. US authorities, including the FBI, are already accelerating their own inquiries into the Murdoch media empire over alleged violations of US law on corrupt payments to foreign officials.

With the arrest of five more senior Sun journalists over the weekend on suspicion of corruption and conspiracy - adding to the four former and current Sun employees arrested last month - a visit to London this week by News Corp's chairman and CEO, Rupert Murdoch, is already being viewed, according to one News Corp executive, as "five-star crisis management" with the future of The Sun on the line.

Sources close to Mr Lewis's legal team have already scheduled key meetings in New York to take place within the next few weeks. Although US investigators have so far found little evidence to support allegations that News Corp journalists illegally accessed the voicemails of 9/11 victims or their families in the US, the FBI have remained focused on allegations of bribery and illegal payments made by News Corp employees.

An email sent to News International staff over the weekend by chief executive Tom Mockridge emphasised that News Corp had "empowered" an independent body, the management and standards committee (MSC), to cooperate fully with the police.

News Corp's board, including Mr Murdoch and his son James, are potentially liable under US corrupt practices law if they knew about or authorised bribes and failed to stop it. The scale of the arrests allied to information supplied to the police by the MSC suggests that News Corp is making it clear to the US Department of Justice that after a decade of silence on illegal practices, it is changing its culture.

However, the expensive legal defence team News Corp has recently hired, including former US Justice Department and White House counsel, suggests that Mr Murdoch is gearing up for a high-profile battle to save his company.

Inside News International's London headquarters, there is growing concern among journalists that the arrests are primarily being made to protect News Corp's global brand. One Sun journalist described Mr Mockridge's email about "due process" as "a sham of emotionally laden drivel".

Although Mr Mockridge claimed that the Sun's editor Dominic Mohan was "committed to leading the paper through this difficult period", The Independent has been told that Mr Mohan has confided to close colleagues he fears that he could soon joins the ranks of those arrested by the Met's specialist unit investigating corruption, Operation Elveden.

Another NI journalist, who asked not to be named, said: "Far from Dominic offering guarantees about leading the paper, he's told some of us he thinks he'll get his collar felt. He said his email traffic was 'colossal' because a lot of people preferred not to knock on his door in the climate. So he may have missed stuff that will be seen as dodgy."

The Sun: the arrests this year

Chris Pharo, Head of news

Graham Dudman, Former managing editor

John Kay Chief reporter. Twice awarded reporter of the year

Fergus Shanahan, Leader writer and executive editor

John Edwards, Picture editor

Nick Parker, Chief foreign correspondent

Mike Sullivan, The Sun's longest-serving crime editor

Geoff Webste, Became deputy editor after moving from the News of the World

John Sturgis, Associate editor, formerly on the news desk

The key players: shining a light on The Sun

Dominic Mohan: The editor of The Sun is said to have told colleagues he fears being arrested as part of the police investigation into his newspaper, because of the immense volume of emails he has seen during his time there, despite being adamant he is not involved in any wrongdoing.

Rupert Murdoch: The News Corporation chairman is expected to fly into London this week to reassure staff at The Sun that he is not about to close the newspaper, but he could face even bigger problems across the Atlantic as phone hacking cases start to arise in the US.