Russian metallurgical giant Norilsk Nickel on Sunday admitted to have improperly pumped wastewater into the Arctic tundra region and said they have suspended workers at a metal plant responsible for the environmental hazard.

In a statement, the company said the incident occurred at the Talnakh enrichment plant near the Arctic city of Norilsk. It said the employees’ decision of dumping wastewater from a dangerously full reservoir into the natural environment, constituted “a gross violation of the factory’s operational protocols”.

“The company is cooperating with Russia’s ecology watchdog Rosprirodnadzor and the Ministry of Emergency Situations to monitor the situation and assess whether any damage has occurred,” it added. “There is no threat of waste leakage.”

The statement came hours after an independent newspaper Novaya Gazeta reported that water tainted with heavy metals from the tailings at a nickel-processing plant were being pumped into a river. Videos shared by the website showed large metal pipes carrying wastewater from the reservoir and dumping foaming liquid at nearby wildlife areas.

According to the newspaper, the factory funnelled the wastewater near the trees and hastily removed their pipes when investigators and emergency services arrived at the site.

This is the second time in a month the company has been connected to causing pollution in the ecologically delicate Arctic region. In May, over 20,000 tonnes of diesel leaked into the Ambarnaya River near the city of Norilsk, after a fuel tank operated by Norilsk Nickel collapsed and spilled into the lake.

On June 4, Russian President Vladimir Putin had declared a state of emergency in northern Siberia after the huge oil spill turned the river crimson and threatened to damage the Arctic environment.