Russia has signed gas and oil agreements with Serbia worth of US$2.2 billion (EUR1.5 billion) Friday.
Some Western leaders fear that the step will help Russia to lock in its role as a major energy supplier to Europe.
Serbia will become an important hub for the distribution of Russian gas. The two deals would help Russia to build and acquire European pipelines, storage facilities, ports and energy companies.
One deal will help to construct a major gas pipeline and storage facilities in Serbia and the other will help Gazprom to acquire a majority stake in NIS, Serbia's state oil company.