LONDON — CNN star interviewer Piers Morgan refused today to disclose details about the most damning links between himself and Britain’s phone hacking scandal – his acknowledgment that he once listened to a phone message left by 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.

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.

Earlier Morgan said he “doesn’t believe” he had ever listened to hacked voicemail message — and dismissed earlier interviews — in which he’d discussed phone hacking at length — as having been based on rumor and hearsay.

He refused to say who had filled him in about the practice.

“My memory’s not great about this. It was a long time ago,” he said.

Before his U.S. television career, Morgan ran two British tabloids — the News of the World and the Daily Mirror. He was giving evidence to Britain’s media ethics inquiry by video link today from the United States — one of a host of tabloid newspaper executives to face the inquiry, set up in the wake of the uproar over phone hacking and other unethical newsgathering methods at the News of the World.

The atmosphere turned tense within minutes of Morgan taking his oath. He was quizzed about his relationship to private investigators and freelancers such as “Benji the Binman,” who specialized in raking though celebrities’ trash to look for scoops.

Morgan said he never dealt with private investigators but he did acknowledge buying information from Benji — and said he’d had some qualms about it.

“Did I think he was doing anything illegal? No. Did I think he was doing anything on the cusp of unethical? Yes,” Morgan said.

The stakes are high for Morgan. More than a dozen journalists have been arrested, senior executives with Rupert Murdoch’s News Corp. media empire have lost their jobs, and top U.K. police officers have resigned over their failure to tackle the scandal.

Witnesses at the inquiry have exposed the seamy side of British journalism, with reporters accused of cooking up stories, blackmailing subjects, hacking phones and paying bribes to police officers to secure tips.