President Vladimir Putin has declared a state of emergency in a region within the Arctic Circle in far northern Russia after 20,000 tons of oil leaked into a river from a power plant.

The spillage occurred on May 29 when the "oil products" leaked from a tank in an industrial plant operated by a subsidiary of Norilsk Nickel, the world's largest producer of palladium and one of the largest producers of nickel, platinum and copper.

"The accident took place at the industrial site of the Nadezhdinski Metallurgical Plant, and part of the spilled petrochemicals, a considerable amount actually, seeped into the Ambarnaya River," Putin said as he discussed the incident with officials on Wednesday, according to the Kremlin. He questioned the measures being taken to clean up the fuel leak that took place near the city of Norilsk in the Krasnoyarsk region, within the Arctic Circle.Discussing how news of the spill emerged in the televised meeting, Putin was reportedly shocked to discover that local authorities had only learned of the incident from social media two days after it happened, and he admonished the region's governor Alexander Uss, Reuters reported.

"What are we to learn about emergency situations from social networks? Are you alright health wise over there?" Putin said, the news agency reported Wednesday. He then reportedly supported a proposal to declare a national state of emergency in the area as it would assist the clean-up effort.

Norilsk Nickel said on its website that "the accident was caused by a sudden sinking of supporting posts in the basement of the storage tank" and that emergency teams "immediately arrived to the site to start clean up works." It said the spill happened in a remote area and that no local community had been impacted.

"A regional emergency situation has been declared in the city of Norilsk and Taymir region. An emergency response team has been set up chaired by the city mayor of Norilsk," the company said, adding that it was trying to limit damage to the local environment. It said a special team had been brought in to deal with the oil spill.

"In total, Norilsk Nickel has mobilized 250 personnel and 72 equipment items to work on the liquidation. As of June 3, a total of 262 tons of diesel fuel has been collected near HHP-3 (the power plant), a total of 800 cubic meters of contaminated soil has been removed and approximately 80 tons of fuel has been collected from the spill to Ambarnaya river," the company said.

Russia's Investigative Committee has launched a probe into the incident that has "caused pollution and environmental damage," it said on its website. A manager at the site has been detained, it said.