One of Piers Morgan's key associates during his editorship of the Daily Mirror told the Leveson Inquiry yesterday it was possible that one of the paper's award-winning scoops - its 2002 revelation of the affair between the then England football manager Sven-Goran Eriksson and TV presenter Ulrika Jonsson - could have been obtained by phone hacking.
Richard Wallace, who was showbiz editor at the Mirror under Morgan and now edits Trinity Mirror's flagship title, also admitted that hacking among the paper's showbiz team - described as commonplace during previous inquiry evidence - may have been "hidden" from him.
The Sunday Mirror's editor, Tina Weaver, also told the inquiry that she could not guarantee that phone hacking had not taken place at her paper.
It is the first time the two executives have admitted that the practice of illegally accessing telephone voicemails could have been happening at their titles.
Last November, former Mirror reporter James Hipwell told Lord Justice Leveson's inquiry into press culture and ethics that phone hacking during the Morgan years was regarded as a "perfectly acceptable way of getting stories" and "a bog-standard journalistic tool".
Wallace was appointed the Mirror's showbiz editor in 1999 and became its head of news a year later. David Barr, the junior counsel to the inquiry, asked him whether he had been aware of phone hacking on the showbiz desk. Wallace: "Not to my knowledge."
Barr: "Can I take it therefore that it's possible that [phone hacking] was going on but hidden from you?"
Wallace replied that it "might well have been".
Of the Eriksson-Jonsson expose, detailed in a book by Morgan, Wallace is described as going into the editor's office and saying: "I think you may need to sit down for this one."
When Wallace was asked about the source of his tip about the affair, he said he could not recall the details. Again, Barr asked if it was "possible" that it was phone hacking? Wallace replied: "It's possible, yes."
Last July, the BBC reported allegations that one reporter on the Sunday Mirror was called the "master of the dark arts". Weaver told the inquiry she believed the claims were untrue.
Lloyd Embley, editor of The People, which is also part of the Trinity Mirror newspaper stable, was a Mirror journalist at the same time as Hipwell. He told the inquiry that he had never seen any phone hacking and said allegations that it was commonplace were "incorrect and unsubstantiated".