US Secretary of State Antony Blinken has warned Washington will act if China does not stop supplying Russia with items used in its assault on Ukraine.

Speaking to the BBC in Beijing, the US's top diplomat said he had made clear to his counterparts they were "helping fuel the biggest threat" to European security since the Cold War.

He did not say what measures the US was prepared to take.

But Mr Blinken was also keen to stress progress had been made in some areas.

He praised Beijing for making efforts in stopping supplies of the drug fentanyl from reaching the US.

China remains the principle source of fentanyl for the US, which the White House has said is causing a public health crisis across the country.

Mr Blinken also stressed he felt Beijing can play a "constructive" role in the Middle East, pointing towards China using "its relationship with Iran to urge" against further escalation in its confrontation with Israel.

The visit - the second in 10 months made by Mr Blinken - forms part of a significant increase in dialogue and diplomacy between these rival powers as they attempt to put relations on an even keel after a period of immense tension last year.

Relations between Washington and Beijing have been strained by China's claims over Taiwan and the South China Sea, and US export bans on advanced tech. They were further damaged by a row over a spy balloon last February.

In recent days, the US passed a law that would force Chinese-owned TikTok to sell the hugely popular video app or be banned in America - something Mr Blinken earlier revealed had not come up in his meeting with China's President Xi Jinping.

Mr Xi - who met Mr Blinken on Friday afternoon in Beijing's Great Hall of the People - agreed the two sides had "made some positive progress" since he met his US counterpart, Joe Biden, in November.

He added the countries should "be partners, not rivals", saying that if the US took "a positive view of China's development", relations could "truly stabilise, get better and move forward".

Mr Blinken told the BBC that one of the key routes for "better relations" between China and both the US and Europe would be for Beijing "or some of its enterprises" to stop providing "critical components" that help Russia make more munitions. The components include items such as "machine tools, micro-electronics, and optics".

"It's helping Russia perpetuate its aggression against Ukraine, but it's also creating a growing threat to Europe because of Russia's aggression," he explained, adding it was "helping to fuel the biggest threat to [Europe's] insecurity since the end of the Cold War".

"We've taken action already against Chinese entities that are engaged in this," he said. "And what I make clear today is that if China won't act, we will."

Mr Blinken - who hinted at sanctions as a possible route - was keen to stress that China was not directly supplying Russia with weapons.

In his interview with the BBC, Mr Blinken said it remained important to see if the two countries could "build greater cooperation in areas where we have mutual interest", including artificial intelligence and military communications.