Serbia would accept an offer to join the Nabucco gas project, but the South Stream project with Russia remains its priority, the head of Serbian state gas company Srbijagas said Wednesday.

"Serbia's priority now is the construction of South Stream, which, unlike Nabucco, has reliable gas sources," Dusan Bajatovic told Belgrade's Politika daily.

Serbia earlier said it was also backing Nabucco in order to contribute to the diversification and security of gas supplies to Europe.

The Western-backed Nabucco pipeline project, estimated at 7.9 billion euros ($11 billion), is designed to pump Central Asian gas via Turkey to Austria and Germany through Bulgaria, Romania and Hungary. The pipeline, intended to bypass Russia, is due to go on stream in 2014.

The Nabucco project is seen as a rival to Russia's South Stream gas pipeline. South Stream, estimated at about 24 billion euros ($34 billion), is designed to annually pump 31 billion cubic meters of Central Asian and Russian gas to the Balkans and onto other European countries, with the pipeline's capacity expected to be eventually increased to 63 bcm annually.

Russia's transit disputes with its former Soviet neighbors have raised concerns in Europe about too much energy dependence on Russia.

Russia cut off gas supplies to Ukraine on January 1 after failing to reach a deal over debt and prices for 2009 in late December, and later halted gas deliveries to Europe, saying Ukraine was stealing transit gas. Kiev denied the accusation.