The ruling in favour of the Congolese state mining firm, Gecamines, is part of a dispute in which the government says it is owed billions of dollars.

It accuses China Molybdenum, the firm that has owned the Tenke Fungurume mine for the past six years, of understating its reserves.

The Chinese company has denied the allegation.

The mine is one of the world's largest sources of cobalt, which is a vital component in batteries for electric cars.