PARIS — A Bouygues manager has been placed under formal investigation, a judicial source said, as part of an ongoing probe into the French construction group's successful bid for a 3.5 billion euro ($3.9 billion) contract to build a new defense ministry headquarters. Investigating magistrates placed the unidentified Bouygues department head under investigation following questioning, the source said late on Saturday. The formal step is akin to the notification of charges, which were not specified. Bouygues said through its lawyer that the company was notified last week that an employee had been summoned for questioning but had yet to be informed of any further steps. “In the absence of other details, the group will not comment on an ongoing investigation,” it said. Dubbed the “French Pentagon,” the new military complex in southwest Paris will house the country's chiefs of staff and core defense departments, which have begun moving in following its completion earlier this year. After a two-year tender, a Bouygues-led consortium was awarded the contract in 2011, beating bids by rival French construction giants Eiffage and Vinci. Two other people, including a former defense official, are already under investigation and facing charges in relation to the probe. According to Le Canard Enchainé newspaper, which broke the original story and successfully defended a defamation suit brought by Bouygues, investigating magistrates suspect a former military real-estate manager of leaking secret documents relating to the tender process via an intermediary. — Reuters