Chinese leader Xi Jinping has said the conflict in Ukraine has "sounded an alarm for humanity", and at the same time condemned US-led sanctions against Russia, accusing the West of provoking Moscow.

Mr Xi was speaking on Wednesday at the opening of a virtual meeting of the world's leading emerging market economies, namely Brazil, Russia, India, China and South Africa, or "BRICS".

His keynote speech reinforced China's ongoing support for Russia in the European conflict, and would have come as welcome news to President Vladimir Putin, who was also in attendance.

"The Ukraine crisis has again sounded the alarm for humanity," the official Xinhua News Agency quoted Mr Xi as saying. 

"Countries will surely end up in security hardships if they place blind faith in their positions of strength, expand military alliances, and seek their own safety at the expense of others," he added. 

In other comments, Mr Xi said imposing sanctions could act as a "boomerang" and a "double-edged sword," and that the global community would suffer from "politicising, mechanising and weaponising" global economic trends and financial flows.

Call to work together on COVID-19 and globalisation

Mr Xi also said China would seek to reduce the damage to international supply chains caused by the COVID-19 pandemic, which it has confronted with a hard-line policy of lockdowns and quarantines, despite a diminishing number of cases and the increasing economic cost.

China's increasingly assertive foreign policy and drive to dominate global markets have prompted a backlash in the US, Europe and elsewhere, including calls to replace Chinese suppliers and reduce reliance on the Chinese economy.

Mr Xi called for nations to work together on such issues, saying efforts to "build a small courtyard with high walls" was in no one's interest.

"Economic globalisation is an objective requirement for the development of productive forces and an irresistible historical trend," Mr Xi said.

"Going backwards in history and trying to block other people's road will only block your own road in the end."

AP