Ribery has already testified, and Benzema is set to be questioned over alleged sexual relations with an underage prostitute operating out of a trendy Paris club.
With France coach Raymond Domenech set to name his squad in about three weeks, the sex scandal could not have come at a worse time for the beleaguered team. It follows a difficult qualifying campaign, during which Ribery was one of the rare players to shine.
Domenech favors tranquility and seclusion at team camps during major tournaments, but the headlines around Europe show no signs of going away. At the World Cup in South Africa, the scrutiny is likely to increase.
Domenech already had tense relations with Benzema - reprimanding him for his attitude during a World Cup qualifier against Romania last September - but has always been close to Ribery.
Although the affair is only at the judicial inquiry stage and no charges have been filed, the damage to their reputations could be lasting.
Questioned by police, the prostitute reportedly said she had sexual relations with Ribery when she was 17, and with Benzema when she was 16, but told both players that she was an adult.
If Ribery and Benzema are charged, they would face up to three years in prison and a $60,000 fine. Prostitution is legal in France, but prostitutes must be over 18 years old, and clients are liable if they are not.
Ribery's lawyer said the footballer provided witness testimony last week for investigators probing a suspected ring operating out of a Champs-Elysees club called Cafe Zaman. Sophie Bottai, Ribery's lawyer, said no charges were filed against her client and he was not held in police custody.
A lawyer for France teammate Sidney Govou - the third player linked to the affair- declined to say whether his client spoke to investigators. Lawyer Thierry Braillard said Govou "never set foot in" Cafe Zaman.
In April, 10 people were taken into custody in the investigation, but none from the national team. Three members of the suspected ring are currently being held for questioning.
French football federation president Jean-Pierre Escalettes and sports minister Rama Yade have refused to comment on the prostitution case.
The scandal comes just as the 27-year-old Ribery considers whether or not to stay at Bayern Munich. He has been linked with moves to Real Madrid, Barcelona and Chelsea, and was set to announce his decision soon.
And Ribery's difficult week got even worse on Wednesday when he was sent off for a crude lunge on Lyon striker Lisandro Lopez in the first leg of the Champions League semifinals. He will miss the return leg next week and possibly the final - if Bayern advances.
Ribery, who was badly disfigured in a car crash when he was a toddler and has refused plastic surgery, rose from amateur-league player with Brest to international star, capturing the hearts of French football fans and the general public.
His ascension was spectacular, and by 2006 he was playing well enough at Marseille for Domenech to pick him in France's team for the World Cup. He has made 42 international appearances, scoring seven goals, including strikes in both qualifiers against Lithuania.
He was one of the few to escape the vitriol from French fans during the 2010 World Cup qualifying campaign. While others were jeered, he was liked.
Ribery, a Muslim convert who is married to a woman of Algerian descent, was viewed as a modest person amid aloof and unreachable football stars. And his zany humor - pretending to be a dummy in a shop window and then surprising German shoppers by screaming at them - ensured huge popularity.
His fall from grace will hurt French football fans at a time when Ribery offered a rare ray of light amid the moribund atmosphere and tiresome football produced by Domenech's team.