Beijing: China is "deeply concerned" that the Ukraine conflict will spiral out of control, foreign minister Qin Gang said on Tuesday, urging certain countries to stop "fueling the fire" in an apparent dig at the US.

Beijing, which signed a "no limits" partnership with Moscow last year, has not condemned Russia's invasion of Ukraine. The US has warned of repercussions if China provides military assistance to Russia, which Beijing denies.

"China is deeply concerned that the Ukraine conflict will escalate or even spiral out of control," Qin said at a foreign ministry forum.

"We urge certain countries to immediately stop fuelling the fire," he said in comments that appeared to be directed at the United States, adding that they must "stop hyping up 'today Ukraine, tomorrow Taiwan'".

"We are adamantly opposed to any form of hegemony, as well as any foreign interference in Chinese affairs."

Qin's remarks came as Russia's TASS news agency reported that China's top diplomat, Wang Yi, would arrive in Moscow on Tuesday, ahead of President Xi Jinping's "peace speech" on Friday, the anniversary of the Ukraine invasion.

Also on Tuesday, China released a paper on Xi's flagship security proposal, the Global Security Initiative (GSI), which aims to uphold the principle of "indivisible security," a concept endorsed by Moscow.

Russia has demanded that Western governments adhere to a 1999 agreement based on the principle of "indivisible security," which states that no country should strengthen its own security at the expense of others.

During a stopover in Hungary on Monday, Wang called for a negotiated resolution to the Ukraine conflict.

On the same day, US Vice President Joe Biden paid a surprise visit to Kyiv in a show of solidarity, promising $500 million in military aid to Ukraine as well as additional sanctions against Russian elites, which will be unveiled in full this week.

Beijing has refrained from condemning Moscow's operation against Ukraine or referring to it as an "invasion," in keeping with the Kremlin's description of the conflict as a "special military operation" designed to protect Russia's own security.

Russia's invasion of Ukraine on February 24 triggered one of the deadliest European conflicts since World War II, as well as the most significant confrontation between Moscow and the West since the 1962 Cuban Missile Crisis.

The United States considers China and Russia to be the two most serious nation-state threats to its security. Xi has supported Russian President Vladimir Putin in the face of Western pressure to isolate Moscow.

On Saturday, US Secretary of State Antony Blinken warned that the US is concerned that China is considering providing "lethal assistance" to Russia, which he told Wang "would have serious consequences in our relationship."

"There are various kinds of lethal assistance that they are at least contemplating providing, including weapons," Blinken told NBC News, adding that Washington would provide more information soon.

The United States sees China and Russia as the two most serious nation-state threats to its security. Xi has supported Russian President Vladimir Putin, defying Western pressure to isolate Moscow.

US Secretary of State Antony Blinken warned on Saturday that the US is concerned that China is considering providing "lethal assistance" to Russia, which he told Wang "would have serious consequences in our relationship."

"There are various kinds of lethal assistance that they are at least contemplating providing, including weapons," Blinken said in an interview with NBC News, adding that Washington would soon release more details.