Copper miner Weatherly International plc (LON:WTI) is confident it can manage groundwater issues at its Tschudi mine in Namibia long term, as the previously flagged problem hit production in its latest quarter.
Output for the three months to September 30 was 3,641 tonnes of copper cathode (March quarter: 4,442 tonnes).
However, nameplate production rates of 1,417 tonnes per month are still expected to be achieved by the end of calendar 2016, the group said.
Chief executive Craig Thomas said: "After recording such a strong performance in the March quarter, we are disappointed that we were unable to anticipate such high groundwater inflow rates at Tschudi, and have consequently spoiled the company's track record of beating our guidance.
"Our operating team however is fully focused on meeting or beating the new revised guidance and on demonstrating once again what they, and the Tschudi operation, are capable of."
Additional costs to deal with the groundwater along with adverse exchange rate movements, meant costs for the quarter increased to US$5,073 per tonne.
The firm added that it continues to engage positively with its main shareholder and lender Orion on the subject of its loan repayments.
Shares fell over 16% to 0.25p.