Russian President Vladimir Putin arrived in Beijing on Friday for the 2022 Winter Olympics and a meeting with Chinese President Xi Jinping, bringing with him a deal to increase natural gas supplies to China amid rising tension with the West, Reuters reported.

Putin told Xi that Russia had prepared a new deal to supply China with an additional 10 billion cubic metres of natural gas, according to a broadcast of their talks aired in Moscow.

Russia, one of the global leaders in hydrocarbon supplies, has been strengthening its ties with China, the world's top energy consumer against the backdrop of Moscow's standoff with the West over Ukraine and other issues.

The broadcast aired in Moscow showed Xi and Putin, neither one wearing a mask, sitting opposite each across a large table in a Beijing state guesthouse, surrounded by masked aides.

"I would like to thank you for the invitation to the opening of the Olympic Games," Putin told Xi. "We know firsthand that this is a huge job. I am sure that our Chinese friends have done it brilliantly, as you always do when preparing such major events."

Xi said the meeting injected new vitality into the relationship, according to the report.

The Olympics, already transformed by the coronavirus pandemic and to be held within a strictly closed loop, have also been overshadowed by the threat of a Russian invasion of Ukraine.

The United States and some of its allies have announced a diplomatic boycott of the Games in protest at China's human rights record. China denies any abuses.

Earlier, China state television footage showed a jet flying with the Russian and Chinese flags. Next to it were jets with Mongolian and Serbian flags. Serbian president Aleksandar Vucic and Prime Minister L. Oyun-Erdene, of Mongolia, are expected to attend the opening ceremony later on Friday.

Qatar's Emir Sheikh Tamim bin Hamad Al Thani and the United Arab Emirates' Crown Prince Sheikh Mohamed bin Zayed Al Nahyan had also touched down, according to state media reports.

Russia and China coordinated their positions on Ukraine during a meeting between their foreign ministers, Wang Yi and Sergei Lavrov, in Beijing on Thursday, the Chinese foreign ministry said.

In response, the United States warned Chinese firms that they would face consequences if they sought to evade export controls imposed on Russia in the event of it invading Ukraine.

"We have an array of tools that we can deploy if we see foreign companies, including those in China, doing their best to backfill US export control actions, to evade them, to get around them," U.S. State Department spokesman Ned Price told a regular news briefing.

Before Lavrov, Beijing had not received foreign political guests for almost two years as it tried to keep the coronavirus out.

Thousands of Russian troops have massed near the border of Ukraine, raising fears of an invasion, which Russia denies planning. Russia has asked NATO to bar Ukraine from joining and to pull out of eastern Europe.