MILAN Shares in London-listed Acacia Mining (ACAA.L) were set to post their biggest ever one-day drop as Tanzania President fired his mining minister following an investigation into possible undeclared exports by mining companies to evade tax.
Tanzania President John Magufuli said the investigation report revealed that Acacia Mining declared the presence of gold, copper and silver in its mineral sand exports but did not declare other precious metals in the consignments.
In a statement earlier on Wednesday, Acacia noted the findings of the investigation but said it had not yet seen a full copy of the report and was seeking further clarification.
"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," the company added in the statement.
By 0231 GMT, Acacia Mining fell 26 percent to its lowest level in nearly one year and on course for its biggest daily since it listed in March 2010.
(Reporting by Danilo Masoni, Editing by Vikram Subhedar)