The exchange marked the first call between the country's top diplomats since the beginning of hostilities marked by heavy Russian bombardment and fierce resistance from Ukrainian fighters who maintain control of the capital Kyiv.

China has walked a cautious diplomatic line since the conflict began, refusing to condemn Moscow's actions after only last month touting a "no limits" friendship between the two countries.

On Saturday, Wang told Secretary of State Blinken: "We encourage direct negotiations between Russia and Ukraine," according to a statement released by the Chinese foreign ministry.

"We hope that the fighting will stop as soon as possible... and that a large-scale humanitarian crisis will be prevented," Wang added, conceding negotiations between the two countries would not be "smooth sailing".

Blinken, meanwhile, said the world was "watching to see which nations stand up for the basic principles of freedom, self-determination and sovereignty," according to State Department spokesman Ned Price.

"The world is acting in unison to repudiate and respond to the Russian aggression, ensuring that Moscow will pay a high price," Blinken said.

But while the US and numerous other countries have imposed a wide range of sanctions against Moscow, China has yet to refer to the crisis as a war.

Wang reiterated the complexity of the issue Saturday, saying it was "closely related to the security interests of all parties".

He added that the US, NATO the European Union and Russia should conduct dialogue and "pay attention to the negative impact of the continuous eastward expansion of NATO on Russia's security environment" -- a key Russian talking point.

Nearly 1.37 million people have fled Ukraine since the start of the invasion, according to the latest UN data.