Chinese state media hailed the "huge potential" of ties with Russia Wednesday after a $85 billion oil deal, with analysts saying the cooperation masks Moscow's unease at Beijing's surging influence in Central Asia.

The framework arrangement between Rosneft, the world's biggest listed crude oil producer, and Chinese oil giant Sinopec was announced during a visit by Russian Prime Minister Dmitry Medvedev, when around 20 agreements in various fields were signed.

Medvedev said in an online chat with Chinese Internet users: "That means 100 million tonnes over the next decade, worth a total of $85 billion.

"This is a large sum of money for any single country, even for China," he added.

"Bilateral relations have never reached such high levels. It is a good thing because we are neighbours," he said in the chat, hosted at the Beijing headquarters of China's official news agency Xinhua.

The government-run China Daily carried the news of his visit on its front page Wednesday, as did the Global Times, which is close to the ruling Communist party.

"China and Russia have supported each other on the global stage on issues of common concern," the paper said in an editorial.

"Their promise of all-round partnership calls for more concerted follow-up efforts. Energy and technological cooperation and mutual investments, in particular, have huge potential to be tapped," it added.

In his online chat, Medvedev said that Russia and China aim to boost their annual two-way trade volume to $100 billion by 2015 and $200 billion by 2020, from $88 billion currently.

Jingdong Yuan, an associate professor of political science at the University of Sydney specialising in Chinese defence and foreign policy, said that from Russia's perspective, "despite the positive developments, China's continued rise remains something Moscow has to swallow and China's growing influence in Central Asia is not something it is happy to see".

"But for the moment, these perceptual and other issues that could divide them have been well managed to allow both to focus on the more positive and also more imminent challenges they face," he added.

In his online chat, Medvedev proclaimed himself a fan of Chinese philosopher Lao Tze and said he believed it was "normal practice" for leaders around the world to disclose their income, assets and property.

The remark that could ruffle feathers among the leadership in China, where campaigners calling for such a move have been detained.

The two countries often cooperate at the UN Security Council nowadays but during the Cold War they were allies at times and divided at others.

Medvedev's visit -- which coincided with journeys to China by Indian Prime Minister Manmohan Singh and Mongolian Prime Minister Norov Altankhuyag -- was due to conclude Wednesday with a trip to the eastern province of Anhui.