A senior Mirror Group journalist admitted hacking voicemails left for Heather Mills by Sir Paul McCartney, Ms Mills has claimed.

The journalist made the admission in 2001, Ms Mills told BBC2's Newsnight programme.

Sir Paul's former wife said that after Sir Paul left the voicemail the journalist rang her quoting parts of the recording.

When challenged about how they knew what was said, Ms Mills said they admitted the message had been hacked.

She told the programme that in early 2001 she had a row with her then boyfriend Sir Paul, who later left a conciliatory message on her voicemail while she was away in India.

According to Ms Mills, a senior Mirror Group Newspapers journalist rang her and "started quoting verbatim the messages from my machine".

She said she challenged the journalist saying: "You've obviously hacked my phone and if you do anything with this story ... I'll go to the police."

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

The journalist was not Piers Morgan, who was the editor of the Daily Mirror at the time, a spokesman for the programme said.

However, the message in question appeared to be the same as one which Mr Morgan later admitted to listening to, the spokesman said.

In a 2006 article in the Daily Mail, Mr Morgan referred to hearing a recorded message which Sir Paul had left for Ms Mills, the spokesman said.

He wrote: "At one stage I was played a tape of a message Paul had left for Heather on her mobile phone".

"It was heartbreaking," Mr Morgan wrote. "The couple had clearly had a tiff, Heather had fled to India, and Paul was pleading with her to come back. He sounded lonely, miserable and desperate, and even sang We Can Work It Out into the answer phone."

If Ms Mills' recollection is correct, the call Mr Morgan listened to had been hacked, and a fellow Mirror Group Newspapers journalist had tried to use it to get a story, the spokesman said.

Ms Mills said: "There was absolutely no honest way that Piers Morgan could have obtained that tape that he has so proudly bragged about unless they had gone into my voice messages."

Newsnight said it had learned that many other prominent people, including footballer Rio Ferdinand and TV presenter Ulrika Jonsson, also believe they were hacked by the Mirror Group.

The spokesman said the programme understands Ferdinand believes an article in 2003 in the Sunday Mirror about his missed drugs test, which appears to have been based on text and voicemail details, involved the hacking of his messages.

And Ms Jonsson has also been told that she was hacked by the Daily Mirror as well as the News of the World in connection with her affair with then England manager Sven-Goran Eriksson in 2002.

Mirror Group Newspapers is part of Trinity Mirror plc which publishes many titles including the Daily and Sunday Mirror, Daily Record and People.

A Trinity Mirror spokesman said tonight: "Our position is clear. All our journalists work within the criminal law and the PCC code of conduct."