An investigation has been launched by environmental authorities in Russia after a river in Siberia turned blood red.
The Daldykan River lies near Norilsk, an industrial centre and one of the most polluted cities in Russia.
While a scientific reason for the change in water colour has yet to be pinpointed, many have blamed the phenomenon on waste from a nearby factory.
Metallurgical plants, owned by regional conglomerate Norilsk Nikel, have been cited by locals on social media as the probable source of the red dye.
A statement released by Sergey Donskoy, head of Russia’s Ministry of Natural Resources, said that according to preliminary information, a possible cause of the pollution was a “breakthrough slurry pipeline” at a Norilsk Nikel plant.
The company responded by denying the pollution was due to an “accidental discharge” at its Nadezhinskogo metallurgical facility but said it is “monitoring the state of the environment in the vicinity of the river”.
Mr Donskoy has ordered the river be checked and for the situation to be brought under the “personal control” of Artem Sidorov, head of the Federal Supervisory Natural Resources Management Service.