The ex-wife of Paul McCartney claimed Wednesday that a journalist at Britain's Mirror Group newspapers admitted hacking into her phone, dragging another tabloid into the long-running scandal.

Heather Mills told the BBC's Newsnight programme that the journalist made the admission in 2001 when he confronted her about an argument she had had with McCartney, who was then still her boyfriend.

Mills said the journalist rang her and "started quoting verbatim the messages from my machine".

"You've obviously hacked my phone and if you do anything with this story -- because they were obviously very private conversations about issues we were having as a couple -- and I said, then I'll go to the police," she challenged him.

She said the journalist responded saying: "OK, OK, yeah we did hear it on your voice messages, I won't run it."

Rupert Murdoch shut down his News of the World tabloid last month after it was revealed that private investigators working for the Sunday paper had hacked into the voicemail of a missing 13-year-old girl who was later found dead.

Former journalists at the Daily Mirror and Sunday Mirror have already claimed that phone hacking was widespread at their papers too, although Trinity Mirror has insisted its staff act within the law.

The Mirror Group comprises the Daily Mirror and the Sunday Mirror, the People, and Scotland's Daily Record and Sunday Mail, while its parent company, Trinity Mirror, owns more than 100 regional titles.

In a statement to the BBC on Wednesday, a spokesman for Trinity Mirror said: "Our position is clear. All our journalists work within the criminal law and the PCC (Press Complaints Commission) code of conduct."

The BBC did not identify the journalist, but confirmed that it was not Piers Morgan, who was editor of the Daily Mirror at the time and is now a celebrity talkshow host on US television network CNN.

However, the broadcaster said the message Mills refers to appears to be the same one which Morgan later admitted to listening to in a 2006 newspaper article.

Morgan has always denied hacking phones, ordering anyone to hack phones, or to his knowledge publishing stories obtained from phone hacking.

Conservative MP Therese Coffey, a member of the Culture, Media and Sport Select Committee investigating phone hacking, said Morgan should return to Britain to explain "very strong" new evidence.

"If Mr Morgan wants to come back to the UK and help them with their inquiries, and I don't mean being arrested in any way, I'm sure he can add more light," she told Newsnight on Wednesday.

"I don't see any point in him necessarily just staying in the US and issuing statements."

Morgan earlier issued a statement through CNN accusing Mills of intercepting voicemails herself.

"I have no knowledge of any conversation any executive from other newspapers at Trinity Mirror may or may not have had with Heather Mills," he said.

"What I can say and have knowledge of is that Sir Paul McCartney asserted that Heather Mills illegally intercepted his telephones, and leaked confidential material to the media."

Although the scandal has so far centred on the News of the World, where a royal editor and a private investigator were jailed in 2007, there is growing evidence that other newspapers may have used the practice.

Trinity Mirror launched an internal review into its editorial practices last month, although it stressed this was not in response to any specific allegation.

McCartney and Mills divorced in 2008.