French mining group Eramet, the world's largest producer of high-grade manganese ore, thanks to its Moanda mine in Gabon Wednesday announced it has ceased all its operations as well as the train transport in Gabon, following overnight events, sending its shares down 18%.

"In view of the events underway in Gabon and as a precautionary measure, the group has activated procedures to ensure the security of its staff and the integrity of its operations...From this morning all Comilog and Setrag operations have been halted and train transport suspended," an Eramet spokesperson told Reuters.

Comilog is a manganese mining unit that is majority owned by Eramet while Setrag is a train transport unit.

"The group is monitoring in real-time how the situation evolves," it said.

Meanwhile, the shares of two other French companies plummeted in the Paris stock exchange on Wednesday in the wake of a reported military coup in Gabon, where they were operating.

Maurel & Prom, Eramet, and TotalEnergies Gabon subsidiary fell by 15% to 20%, according to French financial daily Les Echos.

A group of senior Gabonese military officers appeared on television in the early hours of Wednesday and claimed they had taken power after the state election body announced President Ali Bongo had won a third term.

Eramet is the world’s largest producer of high-grade manganese ore thanks to its Moanda mine in Gabon, with 7.5 Mt of high-grade ore produced in 2022.

The extracted ore is transformed into manganese alloys, which are essential to the production of carbon steel, particularly for the construction and automotive industries.

Eramet shares were down 18% at 62.45 euros ($68) by 0747 GMT.