Shares in gold miner Acacia Mining crashed today after a Tanzanian government report accused the firm of hiding exports from authorities.
Over a quarter has been wiped off the market capitalisation of the FTSE 250 firm in the wake of the findings, as shares dropped 27.11 per cent.
Acacia hit back at the allegations, with the firm saying it "fully declares everything of commercial value that we produce and pay all appropriate royalties and taxes on all of the payable minerals that we produce".
Formerly known as African Barrick Gold, Acacia was banned from exporting both gold and copper by the Tanzanian government in March. Authorities launched an investigation as the government wants to ensure raw material extracted is processed in the east African country.
Acacia is the country's largest gold miner and the ban is costing the firm $1m (£0.8m) a day
The firm said in a stock market statement that it had not seen the full report "which states that the value of minerals within the concentrates in the containers currently at the Dar es Salaam port is more than 10 times the declared amount".
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The group added: "Acacia re-iterates that it fully declares everything of commercial value that we produce and pay all appropriate royalties and taxes on all of the payable minerals that we produce.
"Acacia will provide a further update to the market as soon as practical."