Major companies operating in Sierra Leone include China's Shandong Iron and Steel, which owns the Tonkolili iron ore project. Gerald Group owns the Marampa mines.

Tonkolili has challenged the decision in the country's high court, arguing the grounds to justify the cancellation of its licences were invalid as it had paid all its fees and royalties, the FT said.

Sierra Leone's President Julius Maada Bio, since his election last year, has been reviewing mining contracts and considering changes to the law that would ensure the West African nation benefits from its natural resources.

The Minister of Mines and Sierra Leone's new mining minister Foday Rado Yokie did not immediately respond to emailed requests for comment, while Shandong could not immediately be reached.