The gold bars worth around 1.6 million euros ($2.16 million) were loaded into the cargo hold of an Air France plane at Charles-de-Gaulle airport last Thursday but later disappeared, a source told AFP, confirming earlier French media reports.
Air France said on that it had filed a complaint about the theft.
"We hope the investigations will allow us to quickly determine the sequence of events and identify those responsible," a spokesman said.
The bullion was loaded by Brink’s employees in a shipment similar to others made on a daily basis, the source told AFP.
The employees remained on the tarmac until the plane departed, according to the source.
But Brink’s employees in Zurich only noticed the gold was missing the following day.
Thieves “almost certainly benefited from airport accomplices,” the source told AFP.
Brink’s employs 1,800 security agents in French airports who, in addition to shipping valuable cargo also check passengers, inspect carry-on luggage and cargo carried by planes.