MOSCOW (Reuters) -Russian President Vladimir Putin on Sunday signed a decree clearing the way for Rosbank to purchase stakes in leading Russian companies owned by Societe Generale. The decree said that Rosbank will be able to buy SocGen's stakes in energy producers such as Rosneft and Gazprom, metals companies including Norilsk Nickel and Severstal, and other leading Russian blue chip firms. Societe Generale declined to comment.