MOSCOW, Feb 11 (Reuters) - State-controlled Russian bank VTB (VTBR.MM: Quote) has requested clearance to buy up to 50 percent of Polyus Gold (PLZL.MM: Quote), Russia's largest gold miner, an official at the country's anti-trust watchdog said on Wednesday. Alexei Ulyanov, head of the industrial division of the Federal Anti-Monopoly Service (FAS), told Reuters the request would be denied because the seller had not been disclosed.

Separately, a source close to the negotiations said VTB had requested anti-trust permission to buy 30 percent of Polyus on behalf of a client interested in building a large metals company.

Billionaires Mikhail Prokhorov and Vladimir Potanin each own about 30 percent of Polyus. (Reporting by Oksana Kobzeva and Polina Devitt, writing by Robin Paxton, editing by Aleksandras Budrys)