Meeting in Beijing ahead of the Winter Olympics opening ceremony, the leaders held talks that highlighted their stance as a counter to the US and its allies - and they issued a joint statement with the intention "to resist the interference of external forces".

Putting on a united front and announcing plans to collaborate in a host of areas including space, climate change, artificial intelligence and control of the internet, they said: "Friendship between the two states has no limits, there are no 'forbidden' areas of co-operation."

China said it supports Russia's demands for security guarantees from the West - Moscow has demanded assurances from NATO over Ukraine - and both countries called on NATO to turn its back on "Cold War approaches".

It comes as Russian foreign minister Sergey Lavrov dismissed US claims that Moscow is planning a fake attack to justify an invasion of Ukraine as "nonsense".

Analysis: Putin turns to China and Xi Jinping amid tensions with West

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Mr Xi said China and Russia resolutely support each other when it comes to defending key interests, while Mr Putin praised the "unprecedented" close relations between the two.

Mr Putin's presence at the Games makes him the most high-profile guest in attendance, following a decision by the US, UK and others to not send officials in protest over China's human rights abuses and treatment of Uyghurs and other Muslim minorities.

In televised remarks, the Russian leader praised the close economic ties between the two countries, highlighting a new contract to supply China with 10 billion cubic meters of gas per year from eastern Russia.

The broadcast, which aired in Moscow, showed both world leaders - neither wearing a mask - sitting opposite each other across a large table in a Beijing state guesthouse, surrounded by masked aides.

The two countries had previously coordinated their positions on Ukraine during a meeting between their foreign ministers, Wang Yi and Mr Lavrov, the Chinese foreign ministry said.

Thousands of Russian troops have massed near the border of Ukraine, raising fears of an invasion - something Russia has denied planning, but it has called on the US and its allies to provide a binding pledge that NATO won't expand into Ukraine.

Both countries said they also wanted to see further steps taken to lower the risk of nuclear war - but added that they condemned the creation of AUKUS and other military blocs in the Asia-Pacific region.

The AUKUS partnership, announced last year, saw the UK, Australia and US form a trilateral security pact to develop and deploy nuclear-powered submarines, adding to the Western military presence in the Pacific region amid growing concern over China.

Moscow came out in support of Beijing's stance on Taiwan and said: "The Russian side reaffirms its support for the One-China principle, confirms that Taiwan is an inalienable part of China, and opposes any forms of independence of Taiwan."

Russia and China also expressed concerns about Japanese plans to dump radioactive water from the Fukushima nuclear disaster into the ocean.

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