News Corp backs Rupert Murdoch – but 'witchfinders' trawl emails of staff at Wapping

News Corp's board of directors came out in full support of Rupert Murdoch last night, more than 24 hours after a parliamentary committee described the company's chief executive as unfit to run a major international business.

News Corp said in a statement that the board had full confidence in Mr Murdoch's fitness and support his ability to lead News Corp as chairman and CEO.

"The board based its vote of confidence on Rupert Murdoch's vision and leadership in building News Corporation, his ongoing performance as chairman and CEO, and his demonstrated resolve to address the mistakes of the company identified in the select committee's report," the statement said.

The backing came as it emerged that News Group Newspapers has drawn up a list of 52 staff who it believes may be part of the evidence trail for phone hacking or the illegal gathering of information. Lawyers acting for NGN have said they are searching the emails and documents of the 52 for evidence of criminality relating to thousands of claims by alleged hacking victims. Not all of those included in the searches will be suspected of wrongdoing.

The company is trawling 5.5 million emails and documents belonging to these 52 "data custodians". It is not clear whether all the 52 have direct connections to the News of the World.

News Group originally claimed the hacking scandal was confined to the actions of Clive Goodman, the royal editor who was jailed in January 2007.

Since then, the degree to which his colleagues and bosses were aware of such activities has been the subject of conjecture. A witness statement, written by Linklaters lawyer Christa Band, argues that NGN is doing everything that can reasonably be expected in searching for evidence on behalf of those who claim to have been victims of phone hacking. But lawyers acting for recent litigants are understood to be unhappy that NGN has limited its search to a set list of individuals which the company drew up.

The Linklaters statement makes clear that News Group is struggling to cope with the weight of litigation against it, with 58 different firms of solicitors representing hacking claimants.

The claimants have already incurred £1.73m in common costs plus in excess of a further £10m in individual costs. "NGN remains very concerned at the unrealistically high costs which are being incurred in this litigation," warns the statement.

It also makes clear how hard NGN is fighting cases brought by those who were named in the notebooks of Glenn Mulcaire, the private investigator who was used to carry out phone hacking on a wide variety of targets. "Not every individual who is contacted by the [Metropolitan Police] and informed that they can be identified from Mr Mulcaire's notebooks will have a claim," it states. It notes that Mulcaire might have tracked people down using "conventional forms of inquiry such as internet and electoral roll searching, interrogating databases or making telephone inquiries".

Those whose numbers are listed in Mulcaire's notebooks will have to fight hard to prove they were hacked. "This [number] could have been given to Mulcaire. Equally, it could have been obtained by him as a result of other inquiries," the statement explains.

Lawyers acting for alleged victims have asked NGN to trawl for further evidence but it says the search requests are too broad and that the computer system, which is being operated by PricewaterhouseCoopers, has been struggling to cope.

In a letter to News International staff, Mr Murdoch claimed the company has "gone beyond what law enforcement authorities have asked of us" in investigating phone hacking and other illegality. He said an inquiry into The Times and The Sunday Times by the Management and Standards Committee had found "no evidence of illegal conduct" other than a case of computer hacking which had led to the disciplining of an employee.

News International said last night: "Searching against the number of 52 custodians does not mean that it is considered likely that all of them have relevant documents."