A French prosecutor is arguing that a corruption investigation involving International Monetary Fund chief Christine Lagarde should be dropped.

Lagarde faces preliminary charges of negligence over her role in an arbitration ruling that handed 400 million euros ($531 million) to French businessman Bernard Tapie when Lagarde was French finance minister. The charge could lead to a year in prison and fines.

The prosecutor's office for a special French court handling the case announced Wednesday it wants the case dropped, without elaborating. It is now up to investigating magistrates to determine whether to send Lagarde to trial. Such magistrates often follow prosecutors' recommendations but are not required to.

Lagarde has denied wrongdoing. The probe began before Lagarde became IMF chief in 2011, after predecessor Dominique Strauss-Kahn left under sexual assault allegations.