But “you can’t pretend to be me,” he added. “If you try to pose as me, you go to prison.”

The impersonators often urged targets to quickly and discreetly wire the money to foreign accounts because France was negotiating the release of hostages in Syria and could not publicly use taxpayer money to pay a terrorist ransom.

To reassure the targets, the scammers sometimes went as far as to schedule fake appointments with Mr. Le Drian at the French Parliament or to send fake documents from France’s central bank, purporting to show that the money was being reimbursed.

Delphine Meillet, a lawyer representing Mr. Le Drian, said on Tuesday in an interview with France Inter radio that the scammers were preying upon their targets at a time when fears about terrorism were particularly acute, after a string of deadly attacks in France and the rise of terrorist groups profiting from the war in Syria.

“Imagine: Someone calls you from the defense ministry and says: ‘Would you accept to do France a favor?’” she said, arguing that the scammers had preyed upon the gullibility but also the patriotism of their targets. Those fooled were not promised any monetary profit from the scam.

The scam “could have interfered in political and diplomatic issues and it could have put France in very delicate situations,” she added. “At the time, there really were hostages that needed to be freed.”

Few took the bait. In most cases, suspicious targets balked after checking in with the Defense Ministry, which first alerted investigators in July 2015 that something was afoot.

But three targets were hooked in: Karim Aga Khan IV, the spiritual leader of Ismaili Muslims, who wired over $20 million in March 2016; Corinne Mentzelopoulos, owner of the prestigious Château Margaux wine estate, who sent over $6 million that same month; and Inan Kirac, a wealthy Turkish businessman, who sent $47 million in November and December 2016.