France's national aviation police (GTA) is now investigating how and by whom the gold was stolen from the aircraft, after Air France said it had filed a complaint with police.

"We hope the investigations will allow us to quickly determine the sequence of events and identify those responsible," a spokesman for Air France was quoted by the Local.

Only seven of nine cases handled by the American secure transportation company Brink's reached the final destination in Switzerland onboard the Air France flight last Thursday.

“We are investigating the matter, and especially the possibility that this was an inside job,” a source familiar with the investigation told the British Daily Mail.

Brink's, which provided for the cargo’s security, nonetheless denied being responsible, saying "it was not in charge of the transport and the packages were not under its responsibility when they disappeared," writes the Local.

The firm clarified that their responsibility "was limited to ensure the safety of the consignment during its transit at Charles de Gaulle.”