Ukraine called on China on Saturday to join the West in condemning "Russian barbarism", as Moscow claimed it had struck a Ukrainian arms depot with hypersonic missiles in what would be the first use in combat of the next-generation weapons.
That attack, not far from the country's western Romanian border, came as Russia said its troops had broken through Ukrainian defences to enter the besieged southern port city of Mariupol, a scene of mounting desperation.
With the invasion in its fourth week, Kyiv's embattled leader Volodymyr Zelensky pressed for "meaningful" talks to halt fighting that has forced at least 3.3 million Ukrainians to flee their country.
The plea for China to condemn the invasion came from a top Zelensky advisor, Mikhailo Podolyak.
China could play an important role in global security, he said on Twitter, "if it makes a right decision to support the civilised countries' coalition and condemn Russian barbarism."
Russia's claim Saturday to have unleashed its new hypersonic Kinzhal missile would mark a dramatic new escalation of its campaign to force Ukraine to abandon hopes of closer ties with the West.
Ukrainian air force spokesman Yuri Ignat told AFP that the arms depot in the western village of Deliatyn had indeed been hit but "we have no information of the type of missile".
Russian President Vladimir Putin, who unveiled the Kinzhal missile in 2018, has termed it "an ideal weapon" that flies at 10 times the speed of sound, making it extremely difficult for missile defenses to intercept.
