As the 20-year anniversary of the deaths of Princess Diana and Dodi al-Fayed in a Paris car crash approaches, Dodi's father Mohammad Fayed still believes the tragedy was not an accident.

Al-Fayed, a film producer and jet setter, started dating the Princess of Wales in 1997 although they had been friends for ten years. Their highly-publicised romance was her first since divorcing Prince Charles and made headlines across the globe − mainly because he was an Egyptian Muslim.

In the wake of their deaths, Fayed claimed that it was their cultural differences that tore them apart and ultimately killed them. The tycoon sensationally accused Prince Philip of ordering their murderers to prevent the mother of the future king of England marrying a Muslim.

Fayed's campaign against the Royals led to him funding a £2m documentary - which never aired - claiming that the Duke of Edinburgh had a connection to Nazi Germany.

In 2005, he erected two memorials in Harrods in memory of Dodi and Diana called Innocent Victims. The 3m high bronze statue shows the pair dancing on a beach beneath the wings of an albatross.

Almost two decades on and Fayed believes the pair were just hours from announcing their engagement plans, despite reports that the true love of Diana's life was Dr Hasnat Khan, a British Pakistani heart and lung surgeon who ended his relationship after concluding that a marriage between them would be doomed to failure.

"Mohamed believes they were in love and were going to announce their engagement in London the day after the tragedy," a close friend of the former Harrods boss told the Sun. "He will never get over the death of his son, or that of the Princess — because of the love he had for both."

"Mohamed remains confident that information will emerge confirming his belief that Dodi and Diana were deliberately killed by the security services."

Diana, Princess of Wales and Dodi al-Fayed
A permanent memorial to Diana, Princess of Wales and Dodi al-Fayed is pictured in the Harrods store in London, 31 August 2006, on the ninth anniversary of their death. Diana, 36, and her boyfriend Dodi Fayed, 42, were killed in a car crash in Paris in the early hours of August 31, 1997. Getty

During the inquest into their deaths, Dodi's ex-fiancee, American model Kelly Fisher, had recalled Dodi buying her a "really big engagement ring" but eventually betraying her after he met Diana.

According to another old family friend, Fayed "still misses him terribly" and Dodi's London apartment remains a shrine to him, untouched after 20 years. Now 88, Fayed visits when he wants to feel close to the star-crossed lovers.

"The apartment is cleaned but it is still exactly the same as when Dodi and Diana used to spend time there," the source told the Sun. "They used to sit on the floor having takeaway meals. She and Dodi were mad on films.

"He had a wall filled with VHS tapes. Any moment they had together, they went there. They'd watch TV and hang out like teenagers."