The editors of the Daily Mirror and the Sunday Mirror have conceded that phone-hacking might have occurred at their newspapers.
The Leveson Inquiry into press standards in the UK heard that the interception of voicemail messages could have taken place in the newsrooms of both of the tabloids.
Richard Wallace, who has edited the Daily Mirror since 2004, said the practice might have taken place in the newsroom without his knowledge.
But he insisted that there are “significant positives” in tabloid journalism and he was confident that reporters who work at the newspaper act within the code of practice.
Counsel to the inquiry David Barr asked Mr Wallace if he knew about hacking at the paper.
“Not to my knowledge,” replied Mr Wallace.
Mr Barr asked if it might have occurred without his knowledge.
“It might well have,” said Mr Wallace.
He said it was possible that a story the newspaper ran about Sven Goran Eriksson’s affair with Ulrika Jonsson in 2002 might have come from the interception of voicemail messages.
Mr Wallace, who has worked at the paper for more than two decades, said the tip about the story came from the showbusiness department, adding: “I can’t even recall who actually put the story forward, to be honest.”
Mr Barr asked: “Is it possible, even if you weren’t told, that it was phone hacking?”
Mr Wallace replied: “It’s possible, yes.”
Piers Morgan, who was editor of the paper at the time, flatly denied intercepting Jonsson’s messages when he appeared before the inquiry.
Sunday Mirror editor Tina Weaver told the hearing she was not aware of phone hacking at her newspaper but there was no guarantee that it had not occurred.
Ms Weaver was asked about a BBC article which claimed there was routine phone hacking in the newsroom of the Sunday Mirror.
She said her organisation was “not happy” about the story which contained “anonymous allegations from seven years ago”.
Mr Barr asked her if it was her position that there was “no guarantee” that phone hacking had not occurred at the newspaper. She replied: “That is correct.”