Lawyers acting for beleaguered newspaper group News International have claimed that an IT upgrade erased a key email chain copied to chief executive James Murdoch. The chain referred to "rife" phone hacking at the company.

Linklaters said the 2008 email chain was wiped from Murdoch's computer on 15 January 2011 in an "email stabilisation and modernisation programme", which saw an upgrade from an "unstable" legacy email platform. The claim was made in a letter to the Commons media committee.

Last week, James' father Rupert Murdoch attended meetings at News International and visited its IT department. The nature of his visit is not known.

The email chain copied to James Murdoch detailed claims that phone hacking was "rife" at News International, but Murdoch has said he only read part of the chain, which requested a meeting, and that he was unaware of any hacking.

Linklaters said the email was not previously provided in evidence because of its had been lost.

However, News International has reportedly retrieved a vast tranche of its email archive, known as Data Pool 3 and containing hundreds of millions of messages, and handed it over to police.

The deletion of the email on 15 January 2011 came under two weeks before the Metropolitan Police launched a fresh investigation into the hacking, based on "significant new information" it had received. The email was later found, however, in hard copy form in a storage crate at News International, and on a laptop James Murdoch had stopped using in October 2010.

A high court judge last month heavily criticised News International's email deletion programme, saying the company had wilfully deleted emails that could have shown its journalists' participation in phone and computer hacking.