A French customs officer displays an elephant tusk on June 8, 2016 on Ivry-Sur-Seine near Paris during a press conference after 350 kg of smuggled ivory was seized in one week

French customs said Wednesday that officers had seized over 350 kilogrammes (770 pounds) of elephant tusks in recent weeks, the biggest haul of ivory in the country in ten years.

"We are dealing with organised networks who are slowly destroying African elephants," said Helene Crocquevieille, director general of the customs agency.

The ivory was seized in two separate cases.

Customs agents were alerted to one network when, during a road transport check in September, they discovered four in a car.

Investigations led them to a French-Vietnamese businessman in Paris who had 212 kg of tusks hidden in wooden pallets in his office, which agents discovered on May 25.

Brice Gutermann, head of the customs unit in the western city of Nantes who led the probe, said the suspect had his own company that dealt in beauty products, perfume and selling antiques.

"He used this to organise the trafficking of ivory," said Gutermann.

A dew days later, on June 1, agents at Paris' Charles de Gaulle airport said they intercepted a man on his way from Angola to Vietnam who was carrying 26 elephant tusks, weighing 142 kg, in his luggage.

The passenger was sentenced to 18 months in prison and handed a 140,000 euro ($160,000) fine.

The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) banned the in 1989.

Africa is home to between 450,000 to 500,000 elephants, but more than 30,000 are killed every year on the continent to satisfy demand for , largely in Asia where raw tusks sell for around $1,000 a kilo.