Endeavour Mining Plc says it’s studying the damage from the leak of poisonous liquid at its second-biggest mine located in southern Ivory Coast.

Early reports show that a broken valve leaked 3,000 liters of mud containing cyanide into a canal within the perimeter of the mine, Endeavour’s country manager Laetitia Gadegbeku-Ouattara told journalists in Abidjan Monday.

The contaminated liquid “didn’t leak into the Cavally River,” she said. The company, which took “immediate steps” to prevent the leak from polluting the river, is doing additional analyses to ascertain the scope of the damage, said Gadegbeku-Ouattara.

Cyanide is a poisonous chemical used to extract gold from ore. The Cavally River takes its source from Mount Nimba in Guinea before flowing through Ivory Coast and into the Gulf of Guinea. 

Local authorities have warned residents in the area to abstain from eating fish or drinking from the river until further notice. No human deaths have been reported, said Abdallah Toikeusse Mabri, the president of the Tonkpi region.

Endeavour, whose shares are traded in Toronto and London, where it’s the biggest listed miner, has all its assets in West Africa, with operations in Senegal, Ivory Coast and Burkina Faso. Its Ivorian mine is expected to produce 260,000-290,000 ounces (8.1 to 9.1 tons) of gold this year.

The company’s Ivorian output is expected to increase in the second half of the year with the ramp-up of its Lafigue project in the country’s east.

Endeavour’s shares rose 0.1 per cent Monday in Toronto and 2.1 per cent in London.