Since 2013, Xi and Putin have met more than 40 times. Xi has visited Russia 11 times, while Putin has visited China 13 times, according to Xinhua News Agency.

Zhang Hanhui, China's ambassador to Russia, said that cooperation between the two countries has "yielded fruitful results" and "reached new heights one after another".

The two heads of state have led the deepening of political mutual trust and "maintained close communication and coordination on bilateral relations and major international and regional issues", Zhang wrote in an article published on Thursday.

"This is not only a vivid illustration of the profound friendship between the two heads of state, but also a clear manifestation of the maturity and resilience of China-Russia ties. This provides the most fundamental and reliable guarantee for the long-term, healthy and stable development of China-Russia relations," he added.

Chen Wenling, a veteran economist and senior researcher at the Academy of Contemporary China and World Studies, said the two countries work closely together within multilateral frameworks such as the United Nations, BRICS and the Shanghai Cooperation Organization, and they both oppose hegemony, power politics and unilateralism.

"As two major countries, China and Russia should further play their constructive and leading roles," she said.