• China and Russia's "profound" relationship will not change despite the turbulence in global geopolitics, Chinese President Xi Jinping told his counterpart Vladimir Putin at the opening of the BRICS summit in Kazan on Tuesday.
• "The world today is facing momentous transformations unseen in a century, resulting in a fast-changing and turbulent international landscape," Xi said, according to the English readout of the meeting. "Yet I am confident that the profound and lasting friendship between China and Russia will not change."

China and Russia's "profound" relationship will not change despite the turbulence in global geopolitics, Chinese President Xi Jinping told his counterpart Vladimir Putin at the opening of the BRICS summit in Kazan, Russia, on Tuesday.

The two leaders met at the BRICS summit in Kazan on Tuesday afternoon local time, according to the official readouts from both governments.

"The world today is facing momentous transformations unseen in a century, resulting in a fast-changing and turbulent international landscape," Xi said, according to the English readout of the meeting. "Yet I am confident that the profound and lasting friendship between China and Russia will not change."

Putin also called the Russia-China partnership "one of the main stabilizing factors in the international arena," according to the Kremlin's official readout in English, reiterating his stance during a state visit to China in May.

Both countries have touted their "no-limits" friendship since February 2022 to act as economic and political counterweight to the U.S. global influence.

In his remarks, Xi characterized the China-Russia relationship as "non-alliance, non-confrontation, and not targeting any third party." The two sides had "acted in the spirit of lasting good-neighborliness and friendship" and "kept deepening and expanding" strategic coordination and "all-round practical cooperation," Xi said.

'Signs of strain'

Yet the "friendship without limits" is not without friction, as China tried to position itself as a global player, while walking a tightrope on the Ukraine war by not condemning Russia's invasion.

Beijing has been "careful to not become closely associated" with Russia's war in Ukraine, and to "maintain a facade of impartiality," Eugene Rumer, director and senior fellow at Carnegie's Russia and Eurasia program, wrote in September.

Though Beijing proclaimed the "no limits" friendship with Russia shortly before Moscow launched its invasion of Ukraine, China has not directly provided weapons and ammunition for the war effort.

The summit this week would be "a chance for Moscow to make a show of unity with Beijing amid signs of strain in the relationship," Gabriel Wildau, managing director at Teneo told CNBC on Wednesday.

Wildau also pointed out that China's tightening of export controls for tech and goods with military use earlier this week, ahead of Xi's Russia visit, "sends a signal to Moscow and the rest of the world that there are limits to the Chinese leadership's willingness to enable Putin's war effort."

Russia and North Korea's deepening ties have also put China in an awkward position. Though China joined Russia in pushing back on calls for new sanctions against North Korea, it abstained from voting on a U.N. Security Council resolution to extend a panel monitoring the enforcement of sanctions, which Moscow vetoed.

Still, the mounting economic and diplomatic pressure from the U.S. and its allies could force China closer to Russia, observers have said.

The BRICS summit — which takes place from Tuesday to Thursday — gathered representatives from 36 countries and would be the largest international gathering that Putin has hosted since Russia's full-scale invasion of Ukraine in February 2022.

The economic alliance was initially comprised of Brazil, Russia, India and China in 2009 before South Africa joined in 2010, giving the organization of rapidly economically developing nations its current name. It has since morphed into a geopolitical forum for the world's most powerful nations outside of the West.

BRICS gained more clout after Egypt, Ethiopia, Iran and the United Arab Emirates joined the group in January, with membership to the bloc becoming an attractive prospect for countries looking to boost trade, investment and economic development.

"It's not yet clear whether the grouping can move beyond issuing vague statements of solidarity and function as a mechanism for concerted action," Wildau said, adding that the latest expansion has made the organization "potentially more influential but also more fractious and unwieldy."

Putin is expected to hold a news conference after the summit on Thursday, Reuters reported, citing Kremlin foreign policy aide Yuri Ushakov on Monday.

— CNBC's Holly Ellyatt contributed to this story.