MOSCOW, October 19 (RIA Novosti) - Russia's environmental protection agency has submitted documents on revoking licenses held by the Sakhalin branch of state-controlled oil company Rosneft [RTS: ROSN] to the mineral resources agency, the Natural Resources Ministry said Thursday.

The ministry said serious violations had been revealed during inspections of Sakhalinmorneftegaz's compliance with environmental protection legislation on the oil-rich island in Russia's Far East, which is also the site of the controversial Sakhalin II project led by Anglo-Dutch oil major Shell.

"The Federal Service for the Oversight of Natural Resources has submitted to the Federal Agency for the Management of Mineral Resources documents on revoking production licenses issued to Rosneft-Sakhalinmorneftegaz," the ministry said in a statement.

Environmental experts have established instances of land and water pollution at two major fields being developed by Rosneft - at Katangli and Central Okha, on the northeast coast of the island - and decided to launch an administrative probe into the company's activities in the area.

Russia's environmental authorities have been stepping up pressure on oil producers. In September, the Natural Resources Ministry withdrew a key permit for Shell's Sakhalin II, being implemented under a product-sharing agreement dating back to 1994.

They also warned LUKoil that it might lose at least 20 licenses for failure to develop oil and gas fields in western Siberia and the Urals.

Some analysts say the latest moves are linked to the Kremlin's goal of increasing state control over the energy sector.