Newly-released correspondence in the investigation into phone-hacking has revealed that senior executives at the News of the World (NoW) were warned three years ago that there was "overwhelming evidence" that senior journalists were involved in hacking activities.

The documents – which were published yesterday (1 November) by the Culture, Media & Sport select committee investigating phone-hacking – include a legal opinion sent to NoW legal manager Tom Crone on 3 June 2008 by 11 South Square's Michael Silverleaf QC, group counsel for News Group Newspapers (NGN), which states that evidence obtained from the Metropolitan Police demonstrated that "at least three" of the newspaper's journalists "appear to have been intimately involved."

The opinion relates to the tabloid's attempt to fight legal action brought by Professional Footballers' Association chief executive Gordon Taylor in 2008 for phone-hacking, and suggests that all three reporters were involved in private investigator Glenn Mulcaire's illegal research into Taylor.

Consequently, the letter states the newspaper's prospects of avoiding liability for Taylor's claims of breach of confidence and invasion of privacy were "slim to the point of being non-existent".

Silverleaf goes on to state: "There is substantial surrounding material about the extent of NGN journalists' attempts to obtain access to information illegally in relation to other individuals. In the light of these facts there is a powerful case that there is (or was) a culture of illegal information access used at NGN in order to produce stories for publication."

Publication of the document, alongside communication including emails between Farrer & Co partner Julian Pike and both Crone and former NoW editor Colin Myler, casts a further shadow on previous claims that senior executives believed phone-hacking was limited to one "rogue reporter".

It follows Pike's hearing with the Parliamentary committee last month (19 October) alongside Taylor Hampton Solicitors' Mark Lewis, who has acted for a number of phone-hacking victims.

Pike told the committee that he had seen evidence in 2008 that made it "quite clear… that there was involvement of NoW journalists other than [former royal editor Clive] Goodman."

News Corp parted ways with Farrers last month, appointing Olswang to advise it on all civil claims relating to phone-hacking at the NoW.

Farrers has been the primary adviser to the now-defunct tabloid throughout the phone-hacking scandal, and is understood to have advised on more than 60 cases taken out by alleged victims.

Olswang has now taken over as the main adviser for NGN on all civil claims against the NoW, while also taking responsibility for the implementation of the £20m compensation fund for phone-hacking victims set up by the publisher earlier this year.

Olswang will also continue to advise News International as it draws up a new code of practice, a mandate which was announced in July this year.

Click here to view the newly-published correspondence.