The US has urged Chinese President Xi Jinping to press Vladimir Putin to end “war crimes” being carried out by Russia in Ukraine.

White House spokesman John Kirby said Mr Xi should use his influence to press the Russian President to withdraw troops from Ukraine.

The US plea came on Tuesday (AEDT), as Mr Putin hosted his “dear friend” Mr Xi for dinner at the Kremlin, showing off his relationship with his powerful ally, just days after an international court called for the Russian President’s arrest for war crimes in Ukraine.

The US denounced Mr Xi’s visit, saying the timing indicated Beijing was providing Moscow with “diplomatic cover” to commit additional crimes.

Mr Kirby said a ceasefire in Ukraine would not be enough.

“We hope that President Xi will press President Putin to cease bombing Ukrainian cities, hospitals and schools, to halt the war crimes and atrocities and to withdraw his troops,” he said.

“We are concerned that instead China will reiterate calls for a ceasefire that leaves Russian forces inside Ukraine’s sovereign territory and any ceasefire that does not address the removal of Russian forces from Ukraine would effectively ratify Russia’s illegal conquests.”

President Putin and President Xi greeted each other as “dear friend” when they met in the Kremlin. Russian state news agencies later reported they held informal talks for nearly 4½ hours, with more official talks scheduled for Tuesday.

In televised comments after they greeted each other, Mr Putin told Mr Xi he viewed China’s proposals for a resolution of the Ukraine conflict with respect.

He confessed to being “slightly envious” of China’s “very effective system for developing the economy and strengthening the state”.

Mr Xi, for his part, praised Mr Putin’s strong leadership and predicted Russians would re-elect him next year.

The International Criminal Court issued an arrest warrant on Friday accusing Mr Putin of war crimes for deporting children from Ukraine.

Moscow denies illegally deporting children, saying it has taken in orphans to protect them. It opened a criminal case against the court’s prosecutor and judges. Beijing said the warrant reflected double standards.

“That President Xi is travelling to Russia days after the International Criminal Court issued an arrest warrant for President Putin suggests that China feels no responsibility to hold the Kremlin accountable for the atrocities committed in Ukraine,” US Secretary of State Antony Blinken said.

“Instead of even condemning them, it would rather provide diplomatic cover for Russia to continue to commit those grave crimes.”

China has released a proposal to solve the Ukraine crisis, largely dismissed in the West as a ploy to buy Mr Putin time to regroup his forces and solidify his grip on occupied land.

Kyiv, which says the war cannot end until Russia pulls out its troops, has been circumspect towards China, cautiously welcoming Beijing’s peace proposal when it was unveiled last month.

Ukrainian President Volodymyr Zelensky has said that China arming Russia could lead to World War III, but also that he believed Beijing was aware of this risk, implying he thought it was unlikely. He has called for Mr Xi to speak to him.

Mr Putin signed a “no limits” partnership with Mr Xi last year, shortly before the Kremlin leader ordered the invasion of Ukraine.

Mr Putin claims his objective was to end a threat to Russia from its neighbour’s moves towards the West; Kyiv and the West call it an unprovoked attack on an independent state.

Several European Union countries agreed in Brussels on Monday to jointly buy a million rounds of 155-millimetre artillery shells for Ukraine. Both sides fire thousands of rounds a day.

The US announced its latest military aid package, worth $350 million, including more ammunition for HIMARS rocket launchers, howitzers and Bradley Infantry Fighting Vehicles, plus HARM missiles, anti-tank weapons and river boats.

Fierce fighting continued in the eastern Ukrainian town of Bakhmut, where Ukrainian forces have held out since last summer in the longest and bloodiest battle of the war.

Moscow, which has not scored a major victory since August, has launched a massive winter offensive involving hundreds of thousands of freshly called-up reservists and convicts recruited from jails.

Ukraine, which recaptured swathes of territory in the second half of 2022, has kept mainly to defence since November, aiming to deplete Russia’s attacking forces before launching a planned counteroffensive of its own.

On Tuesday, Ukraine’s defence ministry said it had destroyed Russian cruise missiles in the north of the Crimean peninsula intended for use by Russia’s Black Sea fleet.

-with AAP