US Secretary of State Antony Blinken said Monday in Beijing that China had renewed promises not to send arms to Russia to fight in Ukraine, although he voiced concern at the actions of private Chinese firms.

“We – and other countries – have received assurances from China that it is not and will not provide lethal assistance to Russia for use in Ukraine,” Blinken told reporters after two days of talks.

“We have not seen any evidence that contradicts that. What we do have ongoing concerns about, though, are Chinese firms – companies – that may be providing technology that Russia can use to advance its aggression in Ukraine,” he said.

“We have asked the Chinese government to be very vigilant about that.”

Blinken said that China had offered assurances on Russia in “recent weeks” and not exclusively during his visit.

The United States has gone public with allegations that China is considering arms support to Russia, a leading military power which has had to rely on Iran and North Korea since facing tough resistance in Ukraine after its February 2022 invasion.

China has recently stepped up its diplomacy on Ukraine, a move seen sceptically by the United States which believes Russia is looking for diplomatic avenues to legitimise its territorial gains.