Nigeria has been trying to boost the sector as part of efforts to diversify its economy.

A potential merger of the two firms was expected to be completed by October this year.

Metals X suspended operations at Nifty in Western Australia last month.

Indonesia is home to some of the world’s largest deposits of copper, nickel and tin.

Benchmark tin prices have already been the worst performer on the London Metal Exchange this year, sliding 16%.

The International Tin Association and the Responsible Minerals Initiative joined forces to develop clearer guidelines.

The criteria will enable audit firms and their individual auditors to conduct rigorous and consistent checks on whether any smelter has implemented OECD supply chain due diligence.