LONDON (AP) _ Princess Diana helped rescue an Irish vagrant drowning in a lake in a London park, a newspaper reported Thursday.

The London tabloid the Daily Mail, in a story tagged exclusive, said the incident happened Sunday.

Diana, 32, the estranged wife of Prince Charles, had been jogging in Regents Park and was being driven home, the story said. A group of tourists flagged her car down as it was leaving the park, saying someone had fallen into a narrow lake nearby.

Diana, still in running shoes and shorts, told her chauffeur to call police on the car phone. Then she dashed to the bridge, where she was joined by Karl Kotila, 29, a Finnish student living in south London, the paper said.

Kotila, followed by Diana, climbed over the bridge's railing onto the bank of the lake. Kotila passed his backpack and wallet to Diana, then plunged into the 7-foot-deep lake, swam to the unconscious man and towed him to the bank.

Diana and other people who had joined her at the water's edge pulled the man out. Diana helped turn him on his side as Kotila checked his mouth for blockages, the paper said.

Kotila gave him mouth-to-mouth resuscitation until police arrived and officer Derek Caldwell took over. It quoted Caldwell as saying: ''The heartbeat was very, very faint. The princess was there taking a keen interest in attempts to revive him.''

The paper said Kotila told police the man, named as 42-year-old Martin O'Donoghue, had been in the water about eight minutes.

The paper said Diana thanked Kotila and spoke to a friend of O'Donoghue's. It said the friend was understood to have told police that he and O'Donoghue had been drinking.

O'Donoghue was in critical condition in London's University College Hospital, where Diana had twice visited to talk with staff treating him, the paper said.

A switchboard operator at the hospital told The Associated Press that a patient named Martin O'Donoghue had been admitted. She said hospital administrators had said in a statement he was in critical condition, but that they would not comment further until Thursday.

The Daily Mail said O'Donoghue is an Irishman who, according to friends, has lived on the streets of London for 20 years and is often seen begging.

It said he lives under another bridge in Regents Park with seven or eight other vagrants. It said police described O'Donoghue as ''a friendly tramp, not a troublemaker.''

It said police will recommend Kotila for a bravery award.

On Wednesday, Diana's spending habits were the subject of British press reports. A number of British tabloids reported that Charles was furious when he came across a $240,000 tab for Diana's clothes, beauty treatments and travel.

A Buckingham Palace spokeswoman dismissed the accounts as ''just gossip.''