The text of the new law, published by the state-run news agency, also includes increasing the royalty on uranium exports from five percent to six percent.

The law also allows the government to reject a company's valuation if it believed it was too low. It would be entitled to buy the consignment of minerals at the price quoted.

"For the purposes of calculating the amount of royalties payable, the government shall be entitled to reject the valuation," the text of the new law said.

"Where the government rejects the valuation, it shall have the option to buy the minerals at the low value."

(Writing by Katharine Houreld; editing by Alexander Smith)