The publisher of the Sunday Mirror has said it is being investigated for alleged phone hacking carried out by ex-employees.
Trinity Mirror said Scotland Yard has informed its national newspaper publishing subsidiary, MGN Limited, that a probe is being undertaken to see if it is criminally liable for alleged unlawful conduct by former employees at the weekly publication.
The development is believed to be the first formal confirmation that a newspaper group is being investigated as a corporate suspect for the alleged phone hacking activities of its journalists.
Last month it was reported that Rupert Murdoch's News International had been placed under investigation, but the Metropolitan Police has not officially confirmed that claim.
A spokesman said: "Trinity Mirror plc notes that its subsidiary, MGN Limited, publisher of the group's national newspapers, has been notified by the Metropolitan Police that they are at a very early stage in investigating whether MGN is criminally liable for the alleged unlawful conduct by previous employees in relation to phone hacking on the Sunday Mirror.
"The group does not accept wrongdoing within its business and takes these allegations seriously.
"It is too soon to know how these matters will progress and further updates will be made if there are any significant developments."
Several former Trinity Mirror employees have been arrested since the phone hacking scandal was first uncovered.
Former Sunday Mirror editor Tina Weaver, who was employed by the the paper between 2001 and 2012, was arrested in a dawn raid as part of the Metropolitan Police's Operation Weeting inquiry into phone hacking in March.
Lawyers representing victims of phone hacking at that time said they had been contacted by police who confirmed they were looking into fresh claims relating to the now defunct News of the World's feature desk and Trinity Mirror titles.
During his inquiry into press standards, Lord Justice Leveson described former Daily Mirror editor Piers Morgan's claim that he had no knowledge of alleged phone hacking at the newspaper as "utterly unpersuasive", and said the practice may well have occurred at the title in the late 1990s.
Additional reporting by Press Association