The United States warned China after "intense" talks on Monday against helping Moscow in its invasion of Ukraine, while an anti-war protester interrupted Russian state TV news in an extraordinary act of dissent.

Moscow has not captured any of the 10 biggest cities in Ukraine since beginning its incursion on Feb 24, the most significant attack on a European state since World War Two.

It calls its actions a "special military operation" to "denazify" the country and has asked for military and economic aid from Beijing, according to US officials.

Moscow denies that, saying...