A legal bid to clear the name of Henri Paul - the chauffeur blamed for the crash which killed Princess Diana - has been joined by Harrods owner Mohamed Al Fayed.

Hours after Mr Paul's parents went to court, to demand the release of their son's blood for independent DNA tests, Mr Al Fayed announced a parallel action.

Both parties hope to prove that a blood sample used to show Mr Paul was drunk at the wheel did not actually come from him.

Mr Al Fayed, who owns the Paris Ritz where Mr Paul was an employee, said: "I still believe that it was a horrific murder, but one day justice will be done."

The crash, in a Paris underpass on 31 August, 1997, killed Princess Diana, her companion Dodi Al Fayed - the son of the Harrods boss - and Mr Paul.

'Good man'

In what was thought to be their first interview, the Pauls told BBC Radio 4's Today programme that their son had been painted as an assassin.

It's easy to attack a dead man

Giselle Paul

Mr Paul's mother Giselle said: "We want to know the truth. We're certain that our son was not a drunk.

"We don't accept it - for us he was a good man, a good son.

"People say parents are biased and that can be true, but everyone who knew him and lived with him said the same."

She said if her son had been drunk then Dodi Al Fayed's bodyguard would have insisted another driver be used instead.

Mrs Paul added: "We can't prove it. He's dead. It's easy to attack a dead man.

"They said his liver was in perfect condition, and we would have known, we would have seen if he had been drunk."

Error

Mr Paul's parents believe the blood tested possibly came from one of dozens of bodies held at the Paris morgue that night, and may have been a simple error.

Mohamed Al Fayed believes the crash was a "conspiracy"

And they claim levels of carbon monoxide found in the blood sample would incapacitate an adult, proving it was not his blood.

So far the French authorities have refused to release the blood, to the disgust of the parents.

They say they will accept the result of an independent DNA test, if it proves that the sample came from their son.

'Confidence'

On Friday Mr Al Fayed said he had told his lawyers to begin "a parallel legal action on the same issue".

My pleas have so far fallen on deaf ears

Mohamed Al Fayed

He said he was convinced Mr Paul's blood sample had been switched and that his own scientists were refused permission to carry out their own tests.

Mr Al Fayed said investigations should be reopened in Paris and an independent inquiry held in Britain.

"I have great confidence in France and in the French justice system," Mr Al Fayed said in a statement.

"In Britain I have been pleading with the prime minister to hold an independent public inquiry into the crash but my pleas have so far fallen on deaf ears.

"Isn't it time now for us all to have the opportunity to examine all the facts surrounding this terrible tragedy in a spirit of openness and honest inquiry?"

'Allegations'

Liberal Democrat MP Norman Baker said he was writing to the French government to ask them to support the Pauls and allow an independent blood sample.

Mr Baker told the Today programme he thought a conspiracy "extremely unlikely" but the tests could close the matter for good.

"The consequence of not having that independent blood sample is we will add cover-up allegations to conspiracy allegations," he said.

The only survivor of the crash was the princess's bodyguard, Trevor Rees-Jones.