According to the broadcaster, Bayrou appeared before an investigative court in Paris on Friday on charges of embezzling budget funds.
The interrogation of the 68-year-old politician reportedly lasted 10 hours.
In September, French Central Bank Deputy Governor Sylvie Goulard testified in this case, launched in summer 2017. Her testimony cost her the post of defence minister. Apart from Goulard, the defendants in the case include former European Affairs Minister Marielle de Sarnez, former Justice Minister Michel Mercier, and several other politicians.