A coroner said yesterday there was no evidence Queen Elizabeth's husband ordered the "execution" of Princess Diana in a 1997 car crash, dismissing the conspiracy theories of her late lover's father.

Lord Justice Scott Baker, the coroner at the inquest into her death, described several witnesses as liars and dismissed allegations made by Mohamed Al Fayed, whose son Dodi also died when their car crashed in Paris as paparazzi pursued them.

Mr Fayed, the owner of the luxury Harrods department store in London, had suggested Dodi and Diana were killed by British security services on the orders of Queen Elizabeth's husband, Prince Philip, because the royal family did not want the mother of the future king having a child with his son.

After almost six months listening to more than 250 witnesses, the judge told the jury in his summing up: "There is no evidence that the Duke of Edinburgh ordered Diana's execution and there is no evidence that the security intelligence service or any other government agency organised it".

The judge said he had decided not to call Prince Philip as a witness because the evidence "provided no basis whatsoever in suggesting that he was involved in killing his daughter-in-law".

The inquest was delayed for 10 years because Britain had to wait for the French legal process and then a British police investigation to run their course before it could begin. Both police inquiries decided it was a tragic accident because chauffeur Henri Paul was drunk and driving too fast. The car crashed in a road tunnel.

Lord Justice Scott Baker set out the possible verdicts the jury could reach, but said: "It is not open to you to find that Diana and Dodi were unlawfully killed in a staged accident".

He said possible verdicts included unlawful killing through gross negligence either by Henri Paul, by "following vehicles" or by both.

Other possibilities were accidental death or an open verdict if the 11-member jury felt there was insufficient evidence to support any substantive verdict.

Lord Justice Scott Baker, who said his summing up could take until tomorrow morning, told the jury that certain witnesses at the inquest had not told the truth.

"One of the regrettable features of this case is the number of people who have told lies in the witness box or elsewhere."

Among those he singled out were Diana's butler Paul Burrell, whose three days of testimony were described by lawyers as being "all over the place".

The judge said: "You will probably want to take with a pinch of salt many things that he said in evidence because of the inconsistencies and, you may think, lies in what he told you".

Mr Fayed had told the court that Dodi and Diana rang him up just one hour before the fatal crash to say they were engaged and she was pregnant.