UPDATE 1-Abramovich buys Norilsk stake to settle shareholder spat

* Norilsk shareholders have been locked in bitter dispute

* Abramovich steps in to act as buffer between shareholders

* Abramovich stake is 7.3 pct, worth about $2 bln

* RUSAL shares down 2 pct, lagging flat broader market

(Recasts, adds details)

HONG KONG, Dec 4 (Reuters) - Russia's RUSAL Plc said on Tuesday billionaire Roman Abramovich has agreed to buy 7.3 percent of Norilsk Nickel, a stake worth about $2 billion, in a move that is aimed at ending a four-year-old power struggle between the two biggest shareholders of the Arctic miner.

Sources said told Reuters last month that Abramovich, the owner of Chelsea soccer club, may step up as a "white knight" to act as a buffer between Russian tycoon Vladimir Potanin, who owns 28 percent of Norilsk Nickel, and Oleg Deripaska, whose aluminium firm RUSAL owns 25 percent.

RUSAL said Abramovich would acquire quasi-treasury shares of world's largest nickel and palladium miner, and that Potanin would become general director and be responsible for management of the company.

Potanin and Deripaska have been locked in a shareholder dispute since the latter's Hong Kong-listed RUSAL bought a one-quarter stake in Norilsk just before the 2008 global crash in a cash-and-stock deal worth around $14 billion.

Loss-making RUSAL is now burdened by $10.7 billion in net debts, while Deripaska never won a real say on the Norilsk board and instead was overruled by Potanin, who launched a series of share buybacks with the backing of company management.

RUSAL said the deal also ensures stability of dividends paid by Norilsk Nickel, which has a market value of nearly $30 billion, for the years 2012, 2013, and 2014.

Shares of RUSAL were down more than 2 percent at HK$4.47 in early trade, lagging a flat broader market, and much lower than its 2010 IPO price of HK$10.80.

(Reporting by Donnny Kwok and Anne Marie Roantree; Editing by John Mair and Edwina Gibbs)