Author Gennady Sokolov argues that she was killed in “a distinctly English murder” contracted out by the British spies.

In the book, to be published in ­Moscow next year, he will say the most likely scenario is that a microchip was planted in her car enabling its steering and brakes to be disabled on a signal from an operative who joined the chasing paparazzi.

He claims: “There will never be documents about it. Never. Those responsible must all have been liquidated. The traces have also gone. Some of the witnesses disappeared in the strangest manner.”

Sokolov, who has many contacts in the Russian secret services, said the MI6 officers had arrived and stayed incognito. “Normally when players of such rank are in the country the host intelligence services are aware about it. Here DST (French counter intelligence) had no idea.

“Our people were following them. After all, they were leading faces of British intelligence. Whatever people say about our guys from Yasenevo (headquarters of Russian foreign intelligence, the SVR) they know their rivals very well.”

Sokolov claimed he had met Russian operatives who were involved in seeking to establish the role of the senior British agents in France.

The presence of MI6 figures was known to the Scotland Yard inquiry into Diana’s death headed by former Metropolitan Police Commissioner Lord Stevens.