Shares in Acacia Mining fell more than 8 percent on Monday after a Tanzanian government investigation team accused the London-listed firm of operating in the country illegally without proper documentation.
Acacia, which could not immediately be reached to comment, has been caught up in President John Magufuli's campaign to reform the mining industry, a key source of foreign exchange for the East African country.
The government has previously accused the company of under-declaring its gold exports and failing to pay some taxes.
Acacia has denied all the accusations. "Acacia Mining Plc has been operating illegally in Tanzania without a certificate of compliance," said Nehemia Osoro, the chairman of the investigating team, when it presented the report to the president in a ceremony broadcast on TV. The report on the mining industry by the investigating committee found the country lost up to 108.5 trillion shillings ($48.59 billion) in revenue from exports of gold and copper concentrates between 1998 and 2017, Magufuli said at the event. ($1 = 2,233.0000 Tanzanian shillings)