Heather Mills, the ex-wife of Paul McCartney, on Wednesday accused newspaper group Trinity Mirror PLC of accessing her voicemail messages in 2001 - an allegation that threatens to widen the scope of the hacking inquiries beyond Rupert Murdoch's News Corp. group and its now shuttered News of the World.
Mills told the BBC that a senior Trinity Mirror journalist - though not Morgan - had acknowledged that her voicemail had been accessed and quoted to her a message left by McCartney after the couple had argued. She has not disclosed which of the group's newspapers she alleges carried out the hacking.
Morgan edited the company's flagship tabloid, the Daily Mirror, between 1995 and 2004, and has denied any involvement in phone hacking.
However, Morgan's opponents point to a 2006 article in which he claims to be have been played a tape of a message McCartney had left on Mills' cell phone. "He sounded lonely, miserable and desperate, and even sang 'We Can Work It Out' into the answerphone," Morgan wrote in the Daily Mail.
In a 2009 interview with BBC Radio 4, Morgan also suggested that most British newspapers had engaged in shady practices to uncover exclusive stories, but did not specifically refer to the illicit access of voicemail messages.
"I simply say the net of people doing it was very wide, and certainly encompassed the high and low end of the supposed newspaper market," Morgan told the BBC.
Labour Party deputy leader Harriet Harman said Morgan had questions to answer over the extent of phone hacking within Britain's media industry.
"The public rightly expects that we will get to the bottom of phone hacking. That's why it is so important that the police investigation looks at all the evidence and leaves no stone unturned," Harman said.
John Whittingdale, chairman of Parliament's Culture, Media and Sport committee, which has examined Britain's phone-hacking scandal, said Morgan should return to the U.K. to answer questions - but not from his panel of lawmakers.
He said the panel's remit is focused only on allegations against the News of the World, but that a police inquiry into hacking may be interested to hear from Morgan. "Certainly if there is evidence implicating other newspapers then that needs to be part of that investigation," Whittingdale told Sky News.
Conservative legislator Therese Coffey, a member of Whittingdale's committee, also urged Morgan to return. "I think it would help everybody, including himself and this investigation, if he was able to say more about why he wrote what he did in 2006," she told the BBC's Newsnight program on Wednesday.
In a statement issued Wednesday, Morgan described Mills' claim as "unsubstantiated," and said he had no knowledge of conversations she may have had with a colleague at Trinity Mirror.
"To reiterate, I have never hacked a phone, told anyone to hack a phone, nor to my knowledge published any story obtained from the hacking of a phone," the statement said.