China's President Xi Jinping held his first face-to-face talks with a world leader in nearly two years on Friday, meeting Russian leader Vladimir Putin.
Mr Putin hailed “unprecedented” ties between the neighbours, as tensions grow with the West.
Mr Xi has not left China since January 2020, when the country was grappling with its initial Covid-19 outbreak and locked down the central city of Wuhan where the virus was first detected.
He is now embarking on a flurry of diplomatic activity, as more than 20 world leaders flew in for the Beijing Winter Olympics opening ceremony on Friday.
China hopes the Olympics will be a soft power triumph and a shift away from a build-up blighted by a diplomatic boycott and Covid fears.
The two leaders met in Beijing as their countries seek to deepen relations in the face of increasing criticism from the West.
Russia's ties with China are “developing progressively along the path of friendship and strategic partnership, they are of a truly unprecedented nature”, Mr Putin said in televised remarks at the start of the meeting.
The countries are “an example of a dignified relationship”, he said.
Mr Putin said that before the meeting Moscow had prepared a new contract for the supply of 10 billion cubic metres of natural gas to China from Russia's Far East.
The leaders will attend the Olympic opening ceremony later in the evening.
While Russian officials are banned from attending international sporting competitions over a doping scandal, they may attend if invited by the head of state of the host country.
Spiralling tensions with the West have bolstered ties between the world's largest nation and its most populous, and Mr Putin was the first foreign leader to confirm his presence at the Olympics.
“I have known President Xi Jinping for a long time,” state-owned Chinese broadcaster CCTV quoted Mr Putin as saying on Friday.
“As good friends and politicians who share many common views on solving world problems, we have always maintained close communication.”
China's state-run Xinhua news agency carried an article from Mr Putin on Thursday in which the Russian president painted a portrait of two neighbours with increasingly shared global goals.
He also hit out at the US-led western diplomatic boycott of the Olympics in protest at China's human rights record.
“Sadly, attempts by a number of countries to politicise sports for their selfish interests have recently intensified,” Mr Putin said, calling such moves “fundamentally wrong".
For its part, China has become more vocal in backing Russia in its dispute with Nato powers over Ukraine.
Last week, China's foreign minister Wang Yi called Russia's security concerns “legitimate”, saying they should be “taken seriously and addressed".
Moscow is looking for support after its deployment of 100,000 troops near its border with Ukraine prompted western nations to warn of an invasion and threaten “severe consequences” in response to any Russian attack.
When the communists took power in China in 1949, they were supported by the Soviet Union. However, the two socialist powers later fell out over ideological differences.
Relations got back on track as the Cold War ended in the 1990s, and they have pursued a strategic partnership in recent years that has seen them work closely on trade, military and geopolitical issues.
Those bonds have strengthened further during Mr Xi's presidency.
Among those also attending the Winter Olympics opening ceremony are Saudi Arabia’s Crown Prince Mohammed bin Salman, Egyptian President Abdel Fattah El Sisi, Kazakhstan's President Kassym-Jomart Tokayev and Poland's President Andrzej Duda.
Macron to meet Putin
Meanwhile, French President Emmanuel Macron will meet Mr Putin in Moscow on Monday and Ukraine's President Volodymyr Zelenskiy in Kiev on Tuesday, to discuss the Ukraine situation, as western world leaders try to avoid conflict with Russia over Ukraine.
The French president has said that finding a negotiated path towards de-escalating tensions was a priority.
Mr Macron held phone calls with the Russian and Ukrainian leaders on Thursday to try to make progress on the status of Donbass, the separatist region in eastern Ukraine, as part of efforts to defuse tensions.