Mining giant, Gold Fields Limited and oil giant Kosmos Energy Limited have joined Tullow Oil and MTN Ghana for disputing 'back tax bills' by the Ghana Revenue Authority (GRA).

The two have however declined to give financial details.

Gold Fields spokesman Sven Lunsche said in response to Bloomberg that “Ghana is clearly facing fiscal and economic challenges at the moment”.

“We are hopeful that the government will not resort to unreasonable fiscal measures that will further imperil the challenges facing the corporate sector.”

Gold Fields is in talks with the GRA to resolve the demand for back taxes from 2018 to 2020.

MTN, which has been ordered to pay $776 million in back taxes, has until Friday to reach an agreement with the Ghanaian authorities.

Kosmos Energy, headquartered in Dallas, said the authorities claimed the company underpaid certain taxes and other contractual fiscal obligations.

It maintains that the claim is without merit and will be “vigorously disputed” it if required.