Chinese President Hu Jintao said in Moscow Thursday that energy will remain a "key area" of cooperation between China and Russia as the two countries put the final touches on a major natural gas accord.

"At the moment, documents on gas supplies to China are being finalized," Reuters quoted Russian President Dmitry Medvedev as speaking to reporters in the Kremlin after his meeting with Hu. 

Chinese foreign ministry spokesman Hong Lei said Thursday that energy cooperation is an important part of Sino-Russian ties. 

Moscow's Deputy Prime Minister and energy supremo Igor Sechin told reporters Thursday that negotiations between Russian gas giant Gazprom and China National Petroleum Company had "advanced considerably."

However, Sechin stressed that both sides would have to be patient, given the magnitude of the deal, according to Reuters.

Sources at Gazprom earlier said that Chinese negotiators had signaled they would pay no more than $250 per thousand cubic meters while Russia's gas export monopoly holder hoped the deal with China would prove as lucrative as those passed with European countries.  

The agreement with Russia could also contribute to China's energy diversification strategy, according to a Beijing-based energy expert who declined to be named, noting that Beijing has already inked natural gas deals with Central Asian nations and Myanmar.