ST. PETERSBURG, June 5 (RIA Novosti) - Russian and German energy giants Gazprom and E.ON signed on Friday an agreement to exchange assets in downstream and upstream gas operations.

Under the deal, Gazprom will obtain 49% in the Russian energy trading company E.ON Gerosgas, which holds a 2.93% stake in Gazprom.

In turn, E.ON will receive by the end of 2009 a 25% stake in the authorized capital of Severneftegazprom, the operator of the Yuzhno-Russkoye oil and gas field in west Siberia with recoverable reserves of about 600 billion cubic meters of gas, according to Gazprom.

The deal was signed by Gazprom CEO Alexei Miller and E.ON Ruhrgas CEO Bernard Reutersberg in the presence of Russian President Dmitry Medvedev.

"In implementing the asset swap Gazprom and E.ON have again demonstrated success in the development of long-term Russian-German energy cooperation. From now on our companies will be partners in gas production," Miller said in a statement.

Russia supplies over 35% of Germany's natural gas demand.