PARIS (Reuters) - French billionaire Marc Ladreit de Lacharriere was put under formal investigation on Friday for alleged misuse of company funds in a case involving the wife of former prime minister Francois Fillon, a source close to the investigation told Reuters on Sunday.

France’s financial prosecutor’s office in January began an investigation into Fillon and his wife Penelope over allegations she was paid hundreds of thousands of euros of public funds for work she did not do. This included work for La Revue des Deux Mondes, a French literary review owned by Ladreit’s listed holding Fimalac.

Fillon has said his wife’s work was real, and that he has been the victim of a smear campaign.

Ladreit was first questioned in January about these allegations, a source told Reuters at the time.

The information was first reported by French weekly newspaper Le Journal du Dimanche. A spokeswoman for Fimalac was not immediately available for comment. Fimalac also did not immediately respond to a request for comment from de Lacharriere.