About 21,000 tonnes of diesel leaked into rivers and subsoil near the city of Norilsk on May 29 after a fuel tank at one of the company's thermal power plants apparently subsided. The spill was one of the worst to occur in the Russian Arctic.

Russia's minister of emergency control, Evgeny Zinichev, said a total of 32,000 cubic metres of water-fuel mixture had been collected and placed in tanks, while 103,000 tonnes of contaminated soil had been removed and put in sealed-off hangars.

Vladimir Potanin, Nornickel's president, said the company was "entering a new phase, possibly, more labour-intensive and time-consuming of the utilisation of the soil and water-fuel mixture".

"At present, we are working on transporting the fuel to a location, where it will be separated, and [we are] hoping to complete this over the next two and half or three months," said Potanin.

However, Nornickel said the separation process was yet to be finalised.

"The water-fuel mixture which has been collected will be utilized without harming the environment, with the exact technology is presently being determined," said Nornickel.

Potanin said the company was planning "to leverage on the experience and expertise of its partners from the oil industry".

Russia's president Vladimir Putin told state television the country had no experience of clearing up water pollution on such a large scale, but that Nornickel's response to date had been "truly remarkable".