The News of the World (NoW) hired an ex-police officer to follow two lawyers acting for victims of phone-hacking, according to a report by the BBC's Newsnight.

Taylor Hampton solicitor advocate Mark Lewis and Mishcon de Reya media lawyer Charlotte Harris (pictured) are both understood to have been followed by private investigator Derek Webb during the past 18 months in a bid to prove that they were in a relationship and were sharing confidential information.

Both Lewis and Harris have acted for a number of high-profile phone-hacking clients. Lewis has represented the family of murdered schoolgirl Milly Dowler and Professional Footballers' Association chief executive Gordon Taylor, while Harris has acted for football agent Sky Andrew, actress Leslie Ash and her husband Lee Chapman.

The Newsnight report also states that the Metropolitan Police gave Lewis documents which indicate that a partner from News Group's lawyers, Farrer & Co, had "raised the idea of surveillance".

However, according to the report there is no evidence surveillance was commissioned by Farrers.

The surveillance was also revealed to have involved the filming of members of Lewis' family, including his teenage daughter on a shopping trip.

Lewis told Newsnight that he had "never come across" people investigating the other side's lawyer and that it is "fundamental to the principle of law for being a lawyer – we're meant to be able to represent our client without fear nor favour, but people are actually trying to cause you to have fear."

A News International spokesperson said: "News International's enquiries have led the company to believe that Mark Lewis and Charlotte Harris were subject to surveillance. While surveillance is not illegal, it was clearly deeply inappropriate in these circumstances. This action was not condoned by any current executive at the company."

News Corporation recently replaced Farrers with Olswang to advise it on all civil claims relating to phone-hacking at the NoW. Farrers had been the primary adviser to the now-defunct tabloid throughout the scandal, and is understood to have advised on more than 60 cases taken out by alleged victims.

The news comes as News International chairman James Murdoch prepares to face the Parliamentary committee carrying out the inquiry into phone-hacking again this Thursday (10 November).

Murdoch has instructed Clifford Chance's global head of litigation and dispute resolution Jeremy Sandelson to advise him.