UPDATE 1-Russia's UES sells TGK-6 stake, TGK-7 priced

(Recasts, adds price, quote, details, by-line)

By Olga Popova and Simon Shuster

MOSCOW, March 14 (Reuters) - Russia's former power monopoly said on Friday it had agreed to sell the state's stake in generator TGK-6 for $463 million to two stakeholders, including an investment vehicle of oil and metals magnate Viktor Vekselberg.

TGK-6 TGKF.MM is one of 20 major electricity generating firms being sold off by former monopoly UES EESR.MM as part of reforms aimed at raising investment and introducing competition to the power market.

Another firm UES hopes to spin off called TGK-7 separately said it had set pricing.

For TGK-6, UES said Vekselberg vehicle Integrated Energy Systems (IES) and New Russian Generation would buy the 34.1 percent of the share capital for 0.025 roubles per share.

IES, also known by the Russian acronym KES, already holds 23 percent.

New Russian Generation, a power sector investment fund of Prosperity Capital Management, already owns roughly 20 percent.

"Our stake in the alliance with IES will be a minority stake," said Alexander Branis, head of Prosperity Capital Management. He declined to detail the exact breakdown.