Paul McCartney's ex-wife said Thursday a voicemail that CNN talk-show host Piers Morgan boasted of hearing had been illegally hacked.

Morgan has consistently denied he authorized the use of phone-hacking in his days as a tabloid newspaper editor in Britain. He has not offered an explanation for how he came to hear the message left on Heather Mills' mobile phone.

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The accusation has dragged Morgan into a phone-hacking scandal which has damaged Rupert Murdoch's media empire and has had wide ramifications for the entire British press.

Giving evidence to an inquiry into British media ethics, Mills said she had left a house she shared with McCartney in early 2001 after they had had a row and turned her phone off.

The next morning she said she had received about 25 messages on her phone, all of which appeared to have been listened to, including one in which McCartney "sang a little ditty of one of his songs." She said she deleted the messages.

Later that day, a reporter called her to say he had heard the couple had argued and that McCartney had left a message in which he sang to her. This, she told the inquiry, could only have come from her phone being hacked.

The inquiry was told the unnamed reporter was a former employee from the Trinity Mirror Group though not from the Daily Mirror, one of the group's papers, which Morgan edited from 1995 to 2004.

Asked if she had ever made a recording of McCartney's call or had played it to Morgan herself, Mills said: "Never."

Mills, a former model who married McCartney in 2002 and divorced six years later, said Morgan, "a man that has written nothing but awful things about me for years," would have relished telling the inquiry if she had played a personal voicemail message to him.

Giving evidence in December, Morgan, who bragged about hearing the message in a newspaper column in 2006, refused to say who had played him the recorded message of the call, saying he was protecting a source.

Morgan left open the possibility that the voicemail had been played to him with Mills' approval, but Mills said Thursday that was impossible. "Never," she said. "Never ever."

Morgan also edited the now defunct News of the World tabloid at the center of the hacking scandal from 1994 to 1995, though his tenure was before the practice became rife. He has boasted that he knew about phone-hacking well before the scandal broke, but subsequently said he was referring to rumors.

Morgan has written in his diaries about a "little trick" for eavesdropping on voicemails that he heard of as early as 2001.

One former Mirror employer has told the inquiry hacking was widespread on the paper when Morgan was editor, and Trinity's chief executive has said some reporters might have secretly engaged in the practice.

The phone hacking scandal shook Britain's police, who were accused of failing to investigate allegations that Murdoch's News of the World tabloid had hacked into the phones of thousands of people, including celebrities and murder victims to get stories.

It was also an embarrassment for British Prime Minister David Cameron, who had hired a former News of the World editor as his spokesman.

Reuters, the Associated Press and msnbc.com staff contributed to this report.

Published at 12:15 p.m. ET: LONDON -- CNN star interviewer Piers Morgan refused Tuesday to disclose details about the most damning link between himself and Britain's phone hacking scandal: His acknowledgment that he once listened to a phone message left by former Beatle Paul McCartney for his then-wife Heather Mills.

In a 2006 article in the Daily Mail tabloid, Morgan said he was played a phone message left by the former Beatle on Mills' answering machine, describing it in detail and noting that McCartney "even sang 'We Can Work It Out' into the answerphone." Mills has said there's no way Morgan could have obtained the message honestly.

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On Tuesday, Morgan stubbornly refused to answer almost any questions about how he came to hear the message, saying that doing so would compromise a source. "I'm not going to start any trail that leads to the identification of a source," he said.

Asked by inquiry chief Lord Justice Brian Leveson whether he could supply any information to back the assertion that he had heard the recording legally, Morgan said he couldn't.

Updated at 12:10 a.m. ET: Morgan denies that during his editorship the Daily Mirror newspaper "suppressed" information that cell phones could be hacked in 1998 so that they could use it to spy on celebrities. "Absolute nonsense," he says. 

Updated at 11:50 a.m. ET: Morgan denies any knowledge of paying police officers for information. "I've never been aware of any evidence of that, no," he says.

Updated at 11:30 a.m. ET: "It doesn't necessarily follow that someone listening to someone else is unethical," Morgan says. "It depends on the circumstances in which you are listening to it."

Updated at 11:28 a.m. ET: When asked to discuss the source of a voice mail message of former Beatle Paul McCartney to his then-wife Heather Mills, Piers Morgan refuses.

He also defends the newspaper when it is asserted that the Daily Mirror was among the top offenders of the practice of phone hacking, saying,"You also well know that not a single person has made a formal complaint against a Daily Mirror journalist, so why would you say that?"

Updated at 11:06 a.m. ET: Piers Morgan says the Press Complaints Commission code of practice was displayed prominently in the newsroom at the Daily Mirror, where he was former editor, and says it "informed every editorial decision I made."

When asked whether an editor should have responsibility for his journalists, Morgan says, "The average editor is probably aware of about 5 percent of what journalists are up to at any given time."

Updated at 10:42 a.m. ET: Piers Morgan begins testifying at Britain's Leveson Inquiry into media ethics via videolink from the United States.

• For more details visit breakingnews.com

LONDON -- Former News of the World editor and CNN interviewer Piers Morgan will appear by videolink from the United States on Tuesday at a judge-led investigation into the ethics and practices of Britain's scandal-tarred press.

He is expected to be grilled about comments he has made about widespread phone hacking at tabloid newspapers.

Media mogul Rupert Murdoch's News Corp shut down the News of the World in July after a public outcry over the phone-hacking practices by British journalists at the newspaper.

Morgan's appearance, along with a number of other witnesses Tuesday, has been widely anticipated and critics have been picking through old interviews and Morgan's autobiography "The Insider," in which the 46-year-old Morgan makes clear he knew of phone hacking as long ago as 2001.

• Story: Messages deleted by tabloid journalists? Not so fast...

In an interview for GQ magazine before the public scandal over the practice, Morgan said he couldn't get too upset over hacking because "loads of newspaper journalists were doing it."

And, in an earlier interview for BBC radio unearthed by one of his critics, Morgan appeared to go further, saying it was difficult to condemn private eyes hired to hack into people's phones "because obviously you were running the results of their work."

Morgan maintains that he has never participated in phone hacking or knowingly run a story based on an illegally intercepted message.

"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," he said in a statement in August.

• Official website of the Leveson Inquiry into media ethics

Actors Hugh Grant and Sienna Miller, "Harry Potter" author J.K. Rowling and singer Charlotte Church are among those who have given evidence about press abuse, while executives and lawyers for Murdoch's News Corp have defended the newspaper.

From newspaper man to TV star
Morgan shot to national prominence when he was picked by Murdoch to run the News of the World at age 28. Under his tenure, the tabloid exposed Grant's liaison with Hollywood prostitute Divine Brown and Princess Diana's late-night phone calls to married art dealer Oliver Hoare.

It wasn't all down to good reporting: Morgan has acknowledged that bribes were paid to informants on rival titles.

• Story: Tabloid paid moles at rival papers for scoops?

In 1995, Morgan left the News of the World for the Daily Mirror. His time there was marked by scoops and controversy, including an insider trading scandal.

Among the newspapers to report it was The Independent, which said he allegedly bought 20,000 pounds ($31,000) worth of shares in a technology company the day before it was tipped in the newspaper's investment column. While two other journalists at the Daily Mirror were jailed, Morgan was not charged and kept his job.

However, his editorship at the Daily Mirror ended in 2004 when he ran a faked photograph purporting to show a British soldier urinating on an Iraqi detainee.

Morgan won a second life as a TV personality, eventually signing on as a judge of "America's Got Talent" and taking Larry King's old spot at CNN. So far, he's prospered. Ratings for "Piers Morgan Tonight" have been up 9 percent on last year's figures — good if not spectacular — and he appears to be reaching a younger audience.

CNN spokeswoman Barbara Levin said the network was "extremely pleased" with how Morgan's program was performing and the company has so far stood by its star even as the phone-hacking scandal threatens to draw him in.

'Despicable human being'
"So heartwarming that everyone in U.K.'s missing me so much they want me to come home," Morgan joked earlier this year amid demands he return to give evidence to the Leveson Inquiry.

Morgan's denial that he has had nothing to do with phone hacking is hard to square with a 2006 article in which he said he'd been played a phone message that former Beatle Paul McCartney left for his now ex-wife Heather Mills in the wake of one of their fights.

• Story: Emails warned James Murdoch of phone hacking by tabloid

"It was heartbreaking," Morgan wrote of the tape, saying that McCartney "sounded lonely, miserable and desperate, and even sang 'We Can Work It Out' into the answerphone."

How did Morgan come to hear the tape? He's refused to say, but Mills told the BBC in August that "there was absolutely no honest way" he could have obtained the recording. McCartney echoed her sentiment, saying he'd apparently been hacked.

Morgan's autobiography also abounds with tantalizing references to questionably obtained material: There's "a dodgy transcript of a phone conversation" and a celebrity's stolen laptop.

And when actress Kate Winslet demanded to know how Morgan got her cell phone number, which she had only just changed, Morgan shrugged it off.

"Look, Kate," he joked, "You don't get to be the editor of the Mirror without being a fairly despicable human being."

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The Associated Press contributed to this report.