MOSCOW, April 28 (RIA Novosti) - Russia and Bulgaria will endorse preliminary documents on the South Stream gas pipeline later on Tuesday and sign a final agreement in two weeks, the Russian prime minister said.

The project, designed to annually pump 31 billion cubic meters of Central Asian and Russian gas to the Balkans and on to other European countries, involves Bulgaria, Serbia, Hungary, Italy and Greece.

"This document will be initialed today and signed in a couple of weeks. Russia and Bulgaria have no disagreements," Vladimir Putin said at a news conference with his Bulgarian counterpart.

He added that there had been some "technical" differences between Russian energy giant Gazprom and its Bulgarian partners related to the parties' contractual obligations, but said they were finally ironed out on Monday.

The pipeline is to go on stream in 2013.