Red river near Arctic nickel plant examined by inspectors
Russian environmental inspectors are trying to establish why a river near the Norilsk Nickel industrial complex in the Arctic has turned blood-red.
Dramatic pictures of the discoloured Daldykan river have been posted widely on Russian media.
The government daily Rossiiskaya Gazeta says a leaking slurry pipeline carrying waste copper-nickel concentrate could be to blame.
Norilsk Nickel is the world's largest nickel and palladium producer.
Its vast furnaces were built on the Taimyr Peninsula, in the Krasnoyarsk region of Siberia, in the Soviet era.
The mining group has a production facility called Nadezhda by the Daldykan river. But company officials said they were not aware of any river pollution from the plant.
Billionaire oligarch Vladimir Potanin is president of Norilsk Nickel.