The company said the new policy included "changes to the mining royalty rate and the state's carried interest in minerals projects" and that Atlantic Lithium was in talks with Ghana's Minerals Commission.

In 2011, Piedmont Lithium invested $100 million in the company to secure spodumene, or high-purity lithium ore, from Atlantic Lithium's mine in Ghana.

Piedmont's plans to supply lithium to electric-vehicle maker Tesla will rely in part on the lithium it plans to buy from Atlantic's Ghana operations.

In March, short seller Blue Orca Capital alleged Atlantic Lithium obtained key Ghana mining licenses by making secret payments. The company had rejected the allegations.

(Reporting by Seher Dareen in Bengaluru; Editing by Shounak Dasgupta)