Ms Lagarde has yet to be placed under formal investigation in the case and has denied any wrongdoing.

BBC: IMF 'has confidence' in Christine Lagarde

There is speculation in France that Ms Lagarde could yet be placed under formal investigation in this case, he adds.

BBC: French court summons IMF chief over Bernard Tapie probe

She could be placed under formal investigation for the decision to use arbitration, against advice from senior advisers, to settle a long-running court battle between the state and Mr Tapie, a supporter of the then French President, Nicolas Sarkozy.

BBC: French court questions IMF chief Christine Lagarde