Three men held over 'sex tape blackmail' of heiress

German police arrested three men suspected of attempting to blackmail Susanne Klatten, the country's wealthiest woman, by claiming they had a secret video of her affair with a Swiss gigolo, prosecutors said.

The Munich state prosecutor Thomas Steinkraus-Koch said the trio had been arrested in Duisburg last week on suspicion of trying to extort €800,000 (£690,000) and a luxury BMW from Ms Klatten, the heiress to the BMW empire.

"They sent a letter to her threatening to give the sex video they claimed to have to Italian media if she did not give them [that]," the prosecutor said.

"We assume the story about the video was contrived. At least we have found no evidence of any such video after searching their apartments and computers."

Ms Klatten forwarded the letter to police. An officer posing as one of her acquaintances contacted the men, aged 33 to 46, and set up a contact phone number that led to their arrest.

Ms Klatten, a member of the Quandt family – the leading shareholders in BMW – went public last year with the story of how her Swiss lover had secretly shot intimate footage and later demanded tens of millions of euros to keep quiet.

Helg Sgarbi, a former Swiss investment banker, was sentenced to six years in jail after he admitted he had seduced her at a health club and persuaded her to hand over €7m in €500 notes in a cardboard box. He told the 46-year-old married mother of three that he had paralysed a child in a traffic accident in America and was in need of the money.

Ms Klatten ended the relationship after Sgarbi, 44, demanded more money. He responded by threatening to send photos and tapes of their hotel-room rendezvous to colleagues, family and media unless she gave him €49m. She then went to police.

Forbes magazine estimates Ms Klatten's wealth to be almost $10bn (£6.1bn), making her the 68th richest person in the world.