A Russian metals company says that the waters in a Siberian river turned red last week because of discharge from a metals smelter there.

Norilsk Nickel, the world's largest nickel producer, said in a statement late Monday that a dike at a waste storage facility at its Nadezhdinskaya plant overflowed last week because of torrential rain. The company said the water in the Daldykan river turned red because of iron salts but insisted that it posed no danger to people or animals.

The Russian environmental ministry has pledged to conduct a probe into the incident.

The region has faced environmental issues since the first plant was built there in the late 1930s.