A Russian river has been polluted with an oily and allegedly poisonous substance that turned it emerald green.

Residents in the village of Morozova in the Russian federal subject of Novosibirsk Oblast were horrified when they saw an oil stain on Berd River that turned the water an unnatural green colour.

Local activist Aleksey Nosov, age not disclosed, called the incident an ecological disaster and shared photos of the river on Facebook on 1st July.

He wrote: “This horror was sent to us today by residents of Morozovo. An oil stain of a cloudy chemical slurry spilled in the Berd. The stain stretches several kilometres, and the current slowly carries it to the Ob, poisoning all living things on its way.”

In an interview with the 360 TV channel, Aleksey explained that local residents called all the hotlines of the Ministry of Emergency Situations and other departments, but everyone is allegedly shifting responsibility elsewhere.

360 TV reported that the incident was reported to the regional Ministry of Natural Resources and The Federal Service for Supervision of Natural Resources (Rosprirodnadzor).

Officials took samples of contaminated water to be sent for examination to establish the chemical composition.

However, the results will not be known until next week as the laboratory is independent and there is a backlog.

Rosprirodnadzor officials explained that algae bloom might be to blame, and in that case, it would not pose any danger to people and animals.

The investigation continues.