BEIJING, May 19 (Xinhuanet) -- A mind-boggling sex scandal involving a top motor sports official and the prostitute wife of a British spy has raised urgent questions about the screening procedures employed by the MI5 security service.

    The Sunday Times and Sunday Telegraph reported an MI5 officer had been forced to resign after it came to light his wife was one of five prostitutes who took part in an orgy with Max Mosley, president of Formula One's governing body, the FIA.

    A security source contacted by Reuters did not dispute the reports but said any suggestion the orgy had been an MI5 'sting' operation to entrap Mosley was "nonsense."

    "The service is very busy and constantly stretched by the demands of the threat from AQ (al-Qaida) and other terrorist organizations ...This is not how they're spending their time," he said when asked about the Mosley affair.

    Mosley has been fighting to keep his job after another paper, the News of the World, reported in March he had taken part in what it called a Nazi-style sado-masochistic orgy.

    The 68-year-old FIA president, while apologizing for any embarrassment caused to the sport of motor racing, has strongly denied any Nazi connotation to the affair and said he was the victim of a "covert investigation."

    He asserted after the scandal broke that he had been targeted "by a group specializing in such things, for reasons and clients unknown."

    Mosley, whose father Oswald founded the pre-World War II British Union of Fascists, has resisted calls for his resignation from the FIA but faces a confidence vote by secret ballot in Paris on June 3. The FIA (International Automobile Federation) declined to comment on Sunday's reports.

    (Agencies)