The statement from Havas - which was acquired last year by Vivendi - did not identify the member of staff to which it was referring, and Havas also emphasised the presumption of innocence in its statement.

Vivendi is chaired by French billionaire businessman Vincent Bollore, who has been placed under formal investigation over allegations his company undercharged for work on behalf of presidential candidates in two African nations in return for port contracts.

Bollore has denied any wrongdoing.

A judicial source also said that Groupe Bollore's Chief Executive Gilles Alix was placed under formal investigation for corrupting foreign public officials and complicity in breach of trust, forgery and use of forgery.

The head of the international division at advertising group Havas Jean-Philippe Dorent was placed under formal investigation for breach of trust and forgery, and he is also assisting as a witness in the corrupting of a foreign public official, the source said.

(Reporting by Sudip Kar-Gupta; Editing by Mathieu Rosemain)