Russia’s President Vladimir Putin has declared a state of emergency after 20,000 tonnes of diesel oil leaked into a river within the Arctic Circle.
The spill happened when a fuel tank at a power plant near the Siberian city of Norilsk collapsed last Friday.
President Putin expressed anger after discovering officials only learnt about the incident two days later.
The plant is owned by a subsidiary of Norilsk Nickel, which is the world’s leading nickel and palladium producer.
And in a televised video conference on Wednesday, Mr Putin lambasted the head of the company over its response.
The region’s governor, Alexander Uss, had earlier told President Putin that he became aware of the oil spill on Sunday after “alarming information appeared in social media”.
It has contaminated a 350 sq km (135 sq mile) area, state media report.
Mr Putin has ordered an investigation into the accident and a manager at the power plant has since been detained.
Read more via BBC