Confiscating the assets of companies that have fled Russia after the invasion of Ukraine would shatter investor confidence for decades and take Russia back to the calamitous days of the 1917 Bolshevik revolution, metals magnate Vladimir Potanin said.

Potanin, the biggest shareholder in Norilsk Nickel, the world's largest producer of palladium and refined nickel, said Russia should respond with pragmatism to its exclusion from whole swathes of the global economy.

"We should not try to 'slam the door' but endeavour to preserve Russia's economic position in those markets which we spent so long cultivating," Potanin, the 61-year-old president of Norilsk Nickel, said on the Telegram messaging app.

Potanin said confiscating assets from companies which had left Russia would put the country out in the cold for investors for decades.

"It would take us back 100 years to 1917 and the consequences - a global lack of confidence in Russia from investors - we would feel for many decades," Potanin said.

Besides being the world's largest producer of palladium and high-grade nickel, MMC Norilsk Nickel is a major producer of platinum and copper. It also produces cobalt, rhodium, silver, gold, iridium, ruthenium, selenium, tellurium and sulphur.

Prime Minister Mikhail Mishustin told President Vladimir Putin on Thursday that Russia proposed putting companies that had left Russia into external administration.

The exact mechanisms of that are still unclear, though there is a fierce debate within the Russian elite about how severe Russia's reaction to Western sanctions should be.

Russia's economy is facing the gravest crisis since the 1991 fall of the Soviet Union after the West slapped heavy sanctions on almost the entire Russian financial and corporate system following Moscow's Feb. 24 invasion of Ukraine.

Putin says the "special military operation" in Ukraine is essential to ensure Russian security after the United States enlarged the membership of NATO up to Russia's borders and supported pro-Western leaders in Kyiv.

Ukraine says it is fighting for its existence and the United States, and its European and Asian allies have condemned the Russian invasion. China has called for calm.