A top Scottish pathologist hired by Mohamed al Fayed to challenge evidence that Henri Paul had been drinking before his Paris crash accepted yesterday there may be "compelling evidence" he had.

A top Scottish pathologist hired by Mohamed al Fayed to challenge evidence that Henri Paul had been drinking before his Paris crash accepted yesterday there may be "compelling evidence" he had.

Professor Peter Vanezis said he still had "nagging doubts" about the validity of blood tests taken from Mr Paul's body after the car smash in 1997 in which Diana, Princess of Wales, was killed. But he conceded, at her inquest in London yesterday, that there were "consistencies" between other samples from the body.

The jury heard that a report the eminent forensic medical sciences professor later co-authored concluded Mr Paul had an alcohol problem.

It also suggested that, as a heavy drinker, he may have appeared normal on the night of the crash because he had a higher tolerance than the "average man".

Tests found that Mr Paul, who was at the wheel at the time of the crash on August 31, 1997, was three times the French drink-drive limit.

The Harrods owner - whose son Dodi was killed along with Diana and Mr Paul - disputes the results. He claims samples may have been switched at the Paris morgue to cover up a murder plot orchestrated by intelligence services.

As professor of forensic pathology at Glasgow University, Mr Vanezis founded the university's Centre for International Forensic Assistance in 2001. It was designed to provide expertise of dealing with mass disasters or human rights abuse across the world.

In 2000, he led a team in Kosovo gathering evidence against the Serbian government and also carried out work in Chile and Rwanda.

The professor was hired on behalf of Mr al Fayed two days after the crash to question the initial results.

He was presented at a Harrods press conference in London a few days later offering his expert opinion that the alcohol readings might not be reliable. Other evidence cited at the time included CCTV footage from the Ritz Hotel showing Mr Paul walking around apparently unimpaired by drink - even tying his shoe lace - hours before the crash.

But bar receipts from the hotel suggest he purchased two large measures of Ricard, a strong aniseed spirit. The court heard yesterday that the two measures would have been stronger than four UK shots of whisky.

Mr Vanezis - of Barts and Queen Mary University of London - initially wanted to do a second post mortem examination on Mr Paul but was refused by the French authorities. He did, however, review detailed pathology reports with a group of other experts. Their report concluded: "It may be fairly clearly observed Mr Paul had an alcohol problem and he drank high levels of alcohol regularly."

They added: "There is no doubt that the average man's faculties would have been markedly impaired but a regular drinker like Mr Paul is likely to have been impaired less."

The inquest continues.