A tussle for control of Norilsk Nickel, the world's biggest nickel and palladium producer, could be in prospect after Alisher Usmanov, the Russian billionaire, proposed a merger with his metals group to create a metals and mining giant that analysts valued at $70bn.

The move challenges the intentions of Rusal, the world's biggest aluminium producer, controlled by Oleg Deripaska, to merge with Norilsk itself after acquiring 25 per cent plus one share from Mikhail Prokhorov's Onexim group, one of Norilsk's main shareholders. It could pitch two oligarchs, considered close to the Kremlin, into competition for one of Russia's premier industrial assets.