Diana and Dodi died when their car crashed in a Paris underpass

Dr John Burton told the Times newspaper he could tell the princess was not expecting a baby when he saw her womb.

"I was actually present when she was examined. She wasn't pregnant. I know she wasn't pregnant," he said.

Meanwhile, ex-police chief John Stalker says Prince Charles should be quizzed over a letter in which Diana reportedly said he was plotting to kill her.

The ex-deputy chief constable of Greater Manchester Police said the prince ought to be given the chance to deny the claim, apparently made in a letter Diana wrote about 10 months before she died.

The prince undertook his first public engagement after he was named as the person identified in the letter when he opened a a breast cancer support centre in Hereford, and was met by a supportive crowd.

Even if she got pregnant the first time she met him... the baby would only be six weeks old at most. It doesn't stop everybody wanting to believe it Dr John Burton Charles cheered amid claims

The princess and her boyfriend Dodi Al Fayed died after their car crashed in a Paris underpass in 1997.

On Tuesday it was announced that Britain's top policeman, Metropolitan Police Commissioner Sir John Stevens, would carry out inquiries into the deaths.

The announcement was made by coroner Michael Burgess at the opening and adjourning of a British inquest - the first time the British authorities have formally probed the deaths.

Mr Stalker, who conducted an inquiry into the French investigation and believes the deaths were simply the result of an accident, said: "I believe Sir John should interview Prince Charles.

"It will be unprecedented, but it's an allegation by his former wife that he was planning to kill her.

"It is in everybody's interest that Sir John should put the allegation to Prince Charles so that he can formally deny it."

'Bizarre'

He added that Sir John would probably examine all the "more common" conspiracy theories, such as that the royal family feared Diana was to marry Dodi, a Muslim.

"I think Sir John will investigate every possible theory that is credible, you can't go chasing the thousands on the internet," he said.

It is in everybody's interest that Sir John should put the allegation to Prince Charles so that he can formally deny it John Stalker Profile: Sir John Stevens

Conspiracy theorists have speculated that Diana's alleged pregnancy was a motive behind "plots" to kill her - claims dismissed as "bizarre" by Dr Burton.

Dr Burton, who was one of only two people at Diana's post-mortem, told the Times: "She had only met Dodi six weeks before.

"Even if she got pregnant the first time she met him... he shook hands and got her pregnant, the baby would only be six weeks old at most.

"It doesn't stop everybody wanting to believe it."

At the opening of the inquest on Tuesday, Mr Burgess said: "I am aware that there is speculation that these deaths were not the result of the sad but relatively straightforward road traffic accident in Paris."

He adjourned the inquest for 12 to 15 months to allow time for the police to complete their inquiries, and to consider the vast amount of information from the French investigation.