A prosecutor in Paris on Wednesday called for the case against French football stars Franck Ribéry and Karim Benzema, accused of having sex with an underage prostitute, to be dropped "pure and simple".

Jean-Julien Xavier-Rolai explained to the court in the French capital that it was impossible for the prosecution to prove that the two footballers knew that Zahia Dehar was under the age of 18 when they allegedly paid for sex with her.

Although the age of consent is 15 in France, paying for sex with anyone under 18 is a crime but Dehar, who later gained fame as a lingerie model and designer, had lied about her age.

However, the prosecutor called for five others accused of aggravated pimping in the case to be handed sentences ranging from one year suspended to three years in prison, half of which would be suspended.

News of the investigation into Bayern Munich winger Ribery, now 30, and Real Madrid striker Benzema, 26, broke just before France's disastrous 2010 World Cup campaign.

Ribéry has admitted having sex with Dehar after she was flown to Munich in 2009 as a "present" for his 26th birthday, but insists he could not have known she was not 18 at the time.

Benzema, who is accused of paying for sex with Dehar in a Paris hotel when she was 16, denies that any encounter took place.

The prosecutor himself admitted that "the very reality" of Benzema's encounter is "doubtful".

While the public prosecutor called for the case against Ribéry and Benzema to be dropped, along with that against Ribéry's brother-in-law, the judge ordered it to go ahead due to the fact that Zahia was under 18 at the time in question.

The charges against the duo carry possible prison sentences of three years plus a fine of €45,000 ($61,000). Neither Dehar, who rose to fame under the tutelage of fashion impresario Karl Lagerfeld after the charges emerged, Benzema or Ribéry were in attendance at the hearing, which opened on Monday.   

Speeches from the defence lawyers of each player were expected later on Wednesday, with a decision by the judge expected to be adjourned.