Putin has called for boosting sales of natural resources - Russia's main export - to China, but price has proven to be a sticking point.

Russian Deputy Prime Minister Igor Sechin, who holds sway over Russia's energy sector, said following a meeting with Chinese representatives that Moscow and Beijing are unlikely to agree on the price of Russian gas supplies to China before the middle of next year.

Russia is looking for China to pay prices similar to those Russian gas giant Gazprom charges its European customers, but Beijing wants a discount. The two sides were about $100 per 1,000 cubic meters apart, according to Chinese officials last week.

Wen's trip follows Russian President Dmitry Medvedev's three-day visit to China in September, during which he and President Hu Jintao launched a cross-border pipeline linking the world's biggest energy producer with the largest energy consumer.

Wen said at the press conference that the partnership between Beijing and Moscow has "reached an unprecedented level" and pledged the two countries will "never become each other's enemy".

Over the past year, "our strategic cooperative partnership endured strenuous tests and reached an unprecedented level," Wen said, adding the two nations are now more confident and determined to defend their mutual interests.

"China will firmly follow the path of peaceful development and support the renaissance of Russia as a great power," he said.

"The modernization of China will not affect other countries' interests, while a solid and strong Sino-Russian relationship is in line with the fundamental interests of both countries."

Wen said Beijing is willing to boost cooperation with Moscow in Northeast Asia, Central Asia and the Asia-Pacific region, as well as in major international organizations and on mechanisms in pursuit of a "fair and reasonable new order" in international politics and the economy.

Sun Zhuangzhi, a senior researcher in Central Asian studies at the Chinese Academy of Social Sciences, said the new mode of trade settlement between China and Russia follows a global trend after the financial crisis exposed the faults of a dollar-dominated world financial system.

Pang Zhongying, who specializes in international politics at Renmin University of China, said the proposal is not challenging the dollar, but aimed at avoiding the risks the dollar represents.

Wen arrived in the northern Russian city on Monday evening for a regular meeting between Chinese and Russian heads of government.

He left St. Petersburg for Moscow late on Tuesday and is set to meet with Russian President Dmitry Medvedev on Wednesday.