UPDATE 3-Russian tycoon Usmanov bids for Norilsk - co-owner

(Adds source on Usmanov bid)

By Aleksandras Budrys

MOSCOW, Feb 19 (Reuters) - Russian billionaire Alisher Usmanov has made a bid to merge his assets with Norilsk Nickel (GMKN.MM)(NKELyq.L), which could complicate plans by RUSAL to gain control of the huge Russian metals company.

Norilsk has received a merger proposal from Usmanov, a spokeswoman for Interros, the investment vehicle of billionaire Vladimir Potanin that owns a blocking stake in Norilsk, told Reuters on Tuesday.

"We have received a proposal and Norilsk's board has charged the management to investigate such a possibility," the spokeswoman said.

This was the latest move in a struggle by some of Russia's richest men for control of the world's top nickel and palladium producer after long-term business duo -- Potanin and Mikhail Prokhorov -- decided to split their various assets.

Potanin, whose Interros owns a blocking stake of more than 25 percent plus one share in the metals company, is eager to avoid the sale by former partner Prokhorov of a blocking stake in Norilsk to United Company RUSAL, one of the biggest aluminium producers in the world.

A spokesman for RUSAL, which is controlled by metals magnate Oleg Deripaska, declined to comment, as did a spokesman for Usmanov's Gazmetall.

"I have heard nothing about this move," a source close to the Kremlin told Reuters on condition of anonymity. "Potanin and Prokhorov's split is going according to the previous scheme, but it is unclear how it will all end."