The sex scandal surrounding motor racing chief Max Mosley took a new twist yesterday when newspapers reported that one of the prostitutes involved was married to a British secret service agent.

Formula One's governing body, the International Automobile Federation (FIA), of which Mosley is president, said in a statement that it had noted the reports but had no comment to make.

The Daily Telegraph and Sunday Times reported that the unnamed intelligence officer with Britain's MI5 service had been forced to resign last month after his wife's involvement came to light.

The papers said the woman was one of five prostitutes involved in what the News of the World tabloid newspaper reported in March as a Nazi-style sado-masochistic orgy with the FIA president.

The Telegraph said the agent was understood to have served in the military before joining MI5 where he "had responsibility for watching Al Qaeda suspects, Russian spies, crime bosses and drug lords".

A British security source told Reuters that any suggestion the orgy had been a MI5 'sting' operation to entrap the 68-year-old Briton was "nonsense".

He said MI5 officers had their hands full dealing with national security threats, including from Al Qaeda, and "this is not how they're spending their time".

Yesterday's reports followed Mosley's assertions after the scandal broke that he had been targeted "by a group specialising in such things, for reasons and clients unknown".

Mosley, who will be in Monaco next weekend for the glamour highlight of the Formula One season, has resisted calls for his resignation but faces a confidence vote by secret ballot in Paris on June 3.

The motor racing head, whose father Oswald founded the pre-World War Two British Union of Fascists, has denied any Nazi connotations and is suing the News of the World for unlimited damages for breach of privacy.