Petra Diamonds halted operations at its Williamson mine in Tanzania after the government seized a consignment of diamonds and questioned employees as part of an investigation into the country's mining industry.
Shares in the Johannesburg- and London-listed company were down 8% at 82.65 pence on Monday, having dropped earlier in the session by 28% to their lowest in 21 months.
Petra is the latest miner caught up in a government challenge to the industry, which it accuses of not giving the government a fair share of Tanzania's mineral wealth. Mining accounts for about 4% of Tanzania's GDP.
The diamonds were seized at the airport in Dar es Salaam on August 31 as they were being exported to Antwerp, Belgium.
The Tanzanian government said on Saturday it planned to "nationalise" the diamonds, the value of which it put at $29.5-million. It has accused the miner of underdeclaring its mineral exports.
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