Karim Benzema's place on France's national soccer team could be in jeopardy. Already facing charges of conspiracy to blackmail relating to an extortion scam, Benzema's international career is under increasing strain after teammate Mathieu Valbuena spoke out for the first time against him and the French soccer federation followed up by joining the case as a plaintiff. The investigation, centering on wiretap evidence, started when Valbuena took legal action after being contacted by a man claiming to be in possession of an incriminating sex tape. Benzema's involvement has not yet been fully determined. But investigators who charged him last month believe he was approached by a childhood friend to act as an intermediary and convince Valbuena to deal directly with the blackmailers. The case could have implications on Benzema's career with France's national team. By joining as a plaintiff, the country's soccer federation can have access to the case files. In a statement Friday, it said it "reserves the right, given how the case evolves, to take all the measures needed," including claiming compensation. In an interview with newspaper Le Monde, Vabuena spoke directly about Benzema's attempts to pressure him. "There comes a time when you can't defend the indefensible. I wouldn't even do that to my worst enemy," Valbuena told Le Monde. "When I went to the first hearing I couldn't imagine that Karim was involved in this. I can only feel very, very, very let down and now realize that my relationship with Karim wasn't as sincere as he may claim." Valbuena, who plays for French club Lyon and has made 52 international appearances for France's national soccer team, thinks the video fell into the hands of Axel Angot last year. "He's someone who hangs around players ... I knew about him through Djibril Cisse, when we played together for Marseille," Valbuena said. "I had a new mobile phone and I wanted to change all my contacts. I asked him to transfer all of that from my computer to my new phone because he's good with technology." Benzema and Valbuena were key players in the France team that reached the World Cup quarterfinals last year in Brazil. Benzema, who plays for Real Madrid, has 27 international goals. Even if Benzema is cleared, coach Didier Deschamps may have to leave him out of his European Championship squad in order to preserve team spirit, particularly if he selects Valbuena. In the Le Monde story, Valbuena recounts how Benzema approached him at the team's Clairefontaine training camp in early October, in what he now sees as a clear attempt to initiate a meeting with the blackmailers. "He told me several times that I was dealing with 'some serious thugs.' He told me 'I know that if it was me, with my family and everything ... you'd need to be strong,'" Valbuena said. "OK, he also said 'If you don't want to, leave them to it, no problem. But I can introduce you to my friend.' It always came back to that. I'm more than disappointed. It's quite simply a lack of respect. You don't behave like that with anybody. At the end, when I was just leaving, Karim said 'So what do I do? Shall I give him your number?'" At least four other people have been handed preliminary charges in the case. "Karim knows full well — even if we never spoke about money — that if I go and meet this person it's not for peanuts," Valbuena said. "Deep down I thought it was strange that he wanted me to meet with this person." Benzema called Valbuena again two weeks later. "Not with his phone and not on mine but on one of the Lyon staff members. It was when we were playing Zenit St. Petersburg on October 20 in the Champions League. He said to me 'Mat, my name's got out, what the hell's going on? I can't be dragged into something like this,'" Valbuena said. "Then (Karim) told me 'You're going to have to issue a denial, this will take on huge proportions, I have a daughter and everything.' I told him 'Karim, this didn't come from me. I just filed a complaint (with the police) like any good citizen would. I can't help it if your name came up several times on the phone taps.'" Earlier this month, Europe 1 radio station published a transcript of a recorded conversation between Benzema and a friend. "What he said shows a lack of respect," the 31-year-old Valbuena said. "I respect everyone but I get the impression I've been taken for an idiot." Benzema's lawyer, Alain Jakubowicz, responded on Infosport television Friday saying "the comments made by Mr. Valbuena do not bother us in the slightest" and urged Benzema to respond in order "to show that he is not the man he's portrayed to be." — AP