MOSCOW, October 30 (RIA Novosti) - E.ON Ruhrgas expects to produce 6 billion cubic meters of gas annually at one of Russia's largest gas fields, Yuzhno-Russkoye, the German energy company's CEO said on Friday.

Earlier in the day, E.ON and Russian energy giant Gazprom signed documents closing a deal under which the German company swapped its 3% stake in Gazprom for a 25% share in Yuzhno-Russkoye.

"Apart from long-term gas supply contracts, we are pushing our own production. Natural gas output will fall substantially in the next few decades, while we could produce annually over 6 bcm at the field," Bernhard Reutersberg said after the signing ceremony.

He expressed the hope that E.ON Ruhrgas would manage to push its own natural gas output to 10 bcm by 2012.

The two companies signed an agreement on jointly developing the west Siberian oil and gas field last October, and an asset swap deal in the sphere of natural gas output and trade in June 2009. Å.ON is also Gazprom's partner in the Nord Stream project to build a gas pipeline under the Baltic Sea to Germany.

The Yuzhno-Russkoye field will supply some of its gas to the pipeline expected to go on stream in late 2011.

The deposit has recoverable reserves of 600 billion cubic meters of gas.

E.ON Ruhrgas holds 3.5% in Gazprom through Gerosgaz, and is Gazprom's largest foreign shareholder.