Russia's environment ministry on Wednesday ordered a probe into a possible industrial accident after a river in the far north of the country turned bright red.

In a statement, the ministry said it had received complaints from local residents over "pollution of the river Daldykan in the region of the city of Norilsk by an unidentified chemical that turned the water a bright red colour."

"According to preliminary information

the possible reason for the pollution of the river may be a breakage in a slurry pipe at a Norilsk Nickel plant," it said.

Pictures circulated online earlier by local activist groups showed what they claimed was the blood-red river running through forests in the Russian far north.

Norilsk Nickel - the world's largest producer of nickel and palladium - said it had seen the images of the alleged spillage but insisted there was so far no evidence of any leak. The mining giant said it was monitoring the situation.