The development is thought to be the first formal confirmation that a newspaper group is being investigated as a corporate suspect in relation to alleged phone hacking.
Mirror Group Newspapers is Trinity Mirror’s national newspaper publishing division. Trinity Mirror said on Thursday that the Metropolitan Police had informed it of the investigation.
The group does not accept wrongdoing within its business and takes these allegations seriously.Trinity Mirror spokesman
The probe is examining if the publisher is criminally liable for the actions of the ex-employees.
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.”
Former Sunday Mirror editor Tina Weaver, who worked at the newspaper between 2001 and 2012, was arrested as a part of the Operation Weeting investigation into alleged phone hacking in March.