French police have detained football internationals Franck Ribery and Karim Benzema as part of an investigation into an alleged under-age prostitution ring, legal and police sources say. Earlier, they were questioned at the request of an investigating magistrate looking into allegations that a Paris nightclub gave access to under-age girls working as prostitutes. Police have until Thursday morning to decide whether to release them. Both players have denied wrong-doing. One of the women who is alleged to have met clients at the club while she was under age, Zahia Dehar, has already told investigators that she had paid sex with the two players. Mr Ribery's lawyer told reporters in front of the police station where her client was questioned, that Mr Ribery had had no idea the woman was under 18 when he had paid for sex with her in 2009. "It is an intentional offence, he would have to know her age, which wasn't the case," Sophie Bottai said. "She would have to look minor, which wasn't the case; she would have to tell him she was minor, which wasn't the case, since all over the press she claimed that she was adult and that she was more than 20 years old." Under-age sex illegal Under French law, paid sex with someone under the age of 18 is regarded as sex with a minor - even if the general age of consent is 15 - and punishable by three years in jail and a fine of 45,000 euros (£38,000). Ms Dehar, now 18, said she never told her age either to Mr Ribery, who plays for Bayern Munich, or Mr Benzema, a Real Madrid player. Mr Benzema has previously denied any wrongdoing through his lawyer. Earlier this year, police launched a raid on a Champs-Elysees nightclub called the Zaman Cafe and detained 18 girls on suspicion of prostitution. Ms Dehar was not among them, although her name was already known to investigators, who had been carrying out phone taps on the cafe's managers, says the BBC's Hugh Schofield. Credit: BBC