Joe Biden will warn Xi Jinping the US is prepared to retaliate if Beijing actively supports Russia in Ukraine in a call between the US and Chinese leaders that could represent a pivotal moment in the diplomacy surrounding the war. 

The talks on Friday come as the Biden administration has become increasingly concerned about China’s possible willingness to assist President Vladimir Putin’s invasion, which enters its 23rd day with Russia’s land forces largely at a standstill.

Antony Blinken, the US secretary of state, said that Biden would “make clear that China will bear responsibility for any actions it takes to support Russia’s aggression, and we will not hesitate to impose costs”. Jen Psaki, White House press secretary, told reporters the call was a chance for Biden to see “where President Xi stands”.

Russian rockets hit the outskirts of Lviv on Friday, according to local authorities, in an attack that signalled Moscow’s willingness to expand its bombardment to Ukraine’s west. Andriy Sadovyy, the city’s mayor, said the missiles struck an area near the airport but that no casualties were reported.

Western officials say Putin’s forces have made little progress in capturing territory this week, as troops have been diverted to defend strained supply lines from what UK intelligence services described as “incessant Ukrainian counter-attacks”. 

With Ukraine’s biggest cities still out of Russian control, Putin’s forces have increasingly relied on heavy weapons and missile attacks to grind down resistance, destroying swaths of civilian infrastructure. About 3.2mn Ukrainians have fled the country, representing roughly 7 per cent of the population.

Blinken has warned there are no signs Putin is “prepared to stop” and has reiterated concerns Russia is “setting the stage to use a chemical weapon” and falsely blame Ukraine for the attack.

As Russia has sought to bolster its campaign, the Financial Times reported this week that Moscow had requested several categories of weapons, including drones, from Beijing. Blinken confirmed that Washington was worried China was “considering directly assisting Russia with military equipment” for use in Ukraine.

While Beijing publicly claims to have a neutral stance, the US is concerned the country is moving closer to supporting Russia.

China has also avoided describing the war as an “invasion”, referring instead to the Ukraine “issue” or “crisis”. A foreign ministry official also met Andrey Denisov, Russia’s ambassador in Beijing, to discuss “counter-terrorism and security co-operation” on Thursday.

“The absence of denunciation by China of what Russia is doing . . . flies in the face . . . of everything China stands for, including the basic principles of the UN Charter, including the basic principles of respect for sovereignty of nations,” Psaki said.

“The fact that China has not denounced what Russia is doing, in and of itself, speaks volumes,” she added.

The Biden administration is paying close attention to whether China helps Russia circumvent the sanctions the west has imposed on Putin and his regime.

At a meeting in Rome on Monday, Jake Sullivan, US national security adviser, told his Chinese counterpart Yang Jiechi that Beijing would face consequences for bailing out Russia.

Xi and Putin issued a statement last month in which the leaders described their growing partnership as having “no limits”.

China has called for talks between Kyiv and Moscow and Dmytro Kuleba, Ukrainian foreign minister, signalled in early March that Beijing could play a role as a mediator after speaking with Wang Yi, his Chinese counterpart.

But Beijing has opposed sanctions and consistently blamed Nato and the EU for pressuring Putin ahead of the war. Chinese diplomats and state media have also repeated Russia’s disinformation reports that the US was using Ukraine to research dangerous biological weapons.

Zhao Lijian, China’s foreign ministry spokesperson, told reporters on Thursday that the country’s “clear” aim was to work for de-escalation and end the conflict as soon as possible.

The call is only the fourth interaction between Biden and Xi and follows their virtual meeting in November, when the US president told the Chinese leader the two had a responsibility to make sure that competition did not “veer into conflict”.

The White House concluded last autumn that it was important for Biden to speak directly to Xi due to concerns that messages to his top officials were not being properly relayed to the Chinese president.

Additional reporting by William Langley in Hong Kong