France's Karim Benzema sits on the field after being injured during their friendly soccer match against Armenia at Allianz Riviera stadium in Nice, France, in this October 8, 2015 photo. [Photo/Agencies]

PARIS - French Real Madrid striker Karim Benzema was placed under formal judicial investigation on Thursday in connection with an alleged attempt to blackmail fellow French soccer international Mathieu Valbuena using a sex video.

A statement from the public prosecutor in Versailles west of Paris said the inquiry covered alleged offences that can carry a prison sentence of five years and a fine of 75,000 euros ($81,525).

His lawyer, Sylvain Cormier said that Benzema was totally innocent. "He played no part, I repeat no part, in any blackmail or attempted blackmail," Cormier told reporters.

Cormier added that the nub of the affair was a conversation in which Benzema offered Valbuena a bit of friendly "judicious advice" and what was said had nothing to do with blackmail.

The prosecutor's move, which in France's justice system does not necessarily mean he will end up being tried, but does mean investigators believe they have serious grounds for pursuing the matter with him, exposes Benzema to a period of doubt ahead of a European nations soccer contest, which France hosts next year.

Investigators, who questioned former Liverpool striker Djibril Cisse among others in the same case in mid-October without subsequently placing him under formal investigation, are trying to identify who was behind the alleged extortion attempt.

The affair involved phone-recorded sex footage that could prove embarrassing for Valbuena, according to sources close to the inquiry. Benzema's name came up during phone taps in relation to the inquiry opened last July, police sources say.

The inquiry cites suspicion of complicity in extortion. The prosecutor also ordered Benzema to not make contact with others linked to the affair.

Three other men had been placed under investigation and another person close to Benzema was being questioned by a judge, a source close to the inquiry said.

The investigation could make life difficult for France coach Didier Deschamps, who may wish to call up both Olympique Lyonnais forward Valbuena and striker Benzema to play for hosts France in months ahead and in the June 10-July 10 Euro 2016.