text: The Real Madrid striker appeared before a judge in Versailles after being held in custody overnight.
  His lawyer says he played "no part" in an alleged attempt to extort money from fellow French international Mathieu Valbuena.
  The two men reportedly had an exchange during a training session.
  According to French media, Mr Benzema mentioned the tape to the midfielder during a national team training session at Clairefontaine in early October.
  A source close to inquiry, quoted by told AFP news agency, said the 27-year-old star told investigators on Thursday he had approached Mr Valbuena about the tape on behalf of "a childhood friend".
  France coach Didier Deschamps left both players out of his squad selected on Thursday for matches against Germany and England later in November.
  The prosecutor's office earlier confirmed that Mr Benzema was now under formal investigation for complicity in attempted blackmail and participation in a criminal conspiracy.
  When a suspect is placed under formal investigation, he or she is then examined by a judge, who determines whether there is sufficient evidence for the suspect to be charged.
  If formal charges do follow and he is convicted, Mr Benzema could face a minimum jail sentence of five years, the prosecutor said.
  Meanwhile the court has banned the striker from contacting his France team-mate, or any other people charged in the case.
  Speaking to reporters after the ruling, Mr Benzema's lawyer, Sylvain Cormier, said his client was adamant he was not guilty of the charges.
  "Karim Benzema has nothing to hide," he said.
  "He supports his friend, Mathieu Valbuena, with all his heart. He took no part, I state this again - no part - in the blackmail or blackmail attempts."
  "Karim Benzema will show he acted in good faith, and I hope this will be seen as soon as possible," Mr Cormier added.
  Whether or not the footballer is charged, correspondents say the formal investigation exposes him to a lengthy period of doubt ahead of the Euro 2016 tournament that France hosts next year.
  French coach Deschamps refused to comment on the legal case on Thursday but said Mr Benzema had been injured.
  He added that Lyon midfielder Mr Valbuena was not in an emotional state to play in upcoming games against Germany and England.
  Karim Benzema is the top scorer in the France team, so doubts about his participation at Euro 2016 represent a cloud over Les Bleus as they aim to make the most of their host status.
  The Real Madrid striker has scored 27 goals in 81 appearances for his country, more than double the number scored by fellow France striker Olivier Giroud, and apart from missing out at the 2010 World Cup, has been a mainstay in the team since making his debut in 2007.
  Benzema is regarded as one of Europe's top strikers, but despite winning honours at Real Madrid, he is yet to make a telling contribution at a major tournament for his country.
  Sources have told French media that a relative of Mr Benzema was contacted by the blackmailers, in an attempt to involve him in the scheme against his team-mate. There has been no confirmation from police.
  Three other men have been placed under formal investigation after Mr Valbuena was contacted by someone claiming to have the video.
  It is not the first time Mr Benzema has been involved in a police inquiry. Last year, he and fellow France international Franck Ribery were cleared of accusations they had slept with an under-age prostitute, who later went on to become a reality TV star and fashion designer.
target: French footballer Karim Benzema has been placed under formal investigation in connection with a sex tape blackmail plot involving another player.