The Democratic Republic of Congo’s state miner said it will need to approve any acquisition of cobalt producer Chemaf Resources if the new owner wants to take over a key mining permit.

Chemaf put itself up for sale in September and, although it said in March the process was in its “final stage,” a winning bid is yet to be announced. The Trafigura Group-backed firm is trying to build one of the biggest copper-cobalt mines and processing plants in Congo on a permit rented from state-owned Gecamines.