Acacia Mining, which has three gold mines in Tanzania, has been hit with a demand for $190bn (£145.75bn) in unpaid taxes by the country's authorities, which it described as "inaccurate and unexplainable" in a statement on Tuesday (25 July).
The FTSE 250 miner, which is majority-owned by Canadian firm Barrick Gold, said it had provided a complete declaration all materials mined to the authorities and has paid all royalties and taxes in full.
Earlier this month, Tanzania passed two new pieces of mining legislation bringing about sweeping changes to the legal and regulatory frameworks of the mining industry.
A ban on gold exports has also been in force since March.
Tanzania's tax demand follows a finding by government-appointed committees that Acacia Mining was operating illegally and had understated its gold exports, a charge the company vehemently denies.
"The security of the 36,200 indirect and induced jobs that rely on Acacia's mining operations, as well as the company's ability to invest in education, infrastructure and health projects will all be under threat," it added.
The tax bill consists of $40bn in alleged unpaid taxes and a further $150bn of penalties and interest on funds owed.
Acacia operates three gold mines in Tanzania in the country's Bulyanhulu, Buzwagi and North Mara. The company's shares ended trading in London down 8.40% or 15.50p at 169p.