The exact reason of the leak is yet to be established, but a statement from Norilsk Nickel company, which operates the site suggests it could have been caused - worryingly - by collapsing permafrost.
Worrying videos and pictures show how the pristine polar region of northern Yakutia is ablaze.
Toxic fuel from 21,000 ton leak reaches pristine lake, bypassing floating booms, as rivers of diesel pollution cover-up is exposed.
A 200 metres wide thermocirque is discovered only weeks after scientists find funnel in the Yamal peninsula, caused by build up of methane.
Wildfires on permafrost are ravaging Yakutia - or the Sakha Republic - the largest and coldest entity of the Russian Federation. The scale is mesmerizing. There are some 300 separate fires, now covering 12,140 square kilometers - but only around half of these are being tackled, because they pose a threat to people. The rest are burning unchecked.
Arctic permafrost is degrading much faster than expected, warn scientists from the extreme north of Yakutia. It took two years for a building in the port town of Chersky on the Kolyma River, to snap in the middle after the once solid permafrost could no longer hold its supporting foundation.
Most of the blazes are in a region that saw possibly the hottest-ever temperature above the Arctic Circle this month.
President Vladimir Putin declared a state of emergency last Wednesday, several days after 21,000 metric tons of diesel leaked from a collapsed fuel tank outside the city of Norilsk.The pollution now risks running north into the Arctic Ocean.
Reindeer herders in Russia's Arctic have discovered what scientists say is the first-ever cave bear carcass with soft tissues intact in the region's rapidly thawing permafrost.
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