United States Secretary of State Antony Blinken has raised concerns about China's support for Russia's military, one of the many issues threatening to sour the recent improvement in relations between the world's biggest economies.
Blinken raised the matter during five-and-a-half hours of talks with China's top diplomat Wang Yi in Beijing on Friday - the latest high-level contact between the countries that have eased 2023's acrimony.
"I reiterated our serious concern about the PRC providing components that are powering Russia's brutal war of aggression against Ukraine," Blinken said at a news conference at the end of his visit on Friday, using China's official name, the People's Republic of China.
I had an in-depth and substantive meeting today with People's Republic of China Director Wang Yi. As part of our effort to responsibly manage competition, we discussed areas of difference, in addition to areas of shared interest — like counternarcotics — where we can build on… — Secretary Antony Blinken (@SecBlinken) pic.twitter.com/uGkTh6FPqzApril 26, 2024
"China is the top supplier of machine tools, microelectronics, nitrocellulose - which is critical to making munitions and rocket propellants - and other dual-use items that Moscow is using to ramp up its defence industrial base."
The visit produced little progress on contentious issues including US complaints about cheap Chinese exports and tensions over Taiwan and the South China Sea.
Instead, both sides are focusing on pragmatic issues such as people-to-people exchanges.
Despite its "no limits" partnership with Moscow, China has steered clear of providing arms for Russia's war in Ukraine, but Blinken said its supply of so-called dual-use goods was "having a material effect in Ukraine" and raising the threat Russia poses to other countries in Europe.
Blinken did not respond to a question on whether Washington would impose sanctions over China's support for Russia.
The US officials say such assistance risks hurting the broader bilateral relationship, even as ties stabilise after being hit by then-House Speaker Nancy Pelosi's visit to Taiwan in 2022 and the US downing of a suspected Chinese surveillance balloon in February 2023.
China has said it has not provided weaponry to any party, adding that it is "not a producer of or party involved in the Ukraine crisis".
However, it says that normal trade between China and Russia should not be interrupted or restricted.
In addition to his talks with Wang, Blinken met Chinese President Xi Jinping, who reiterated Beijing's concerns that the US was suppressing its economic development.
"This is a fundamental issue that must be addressed, just like the first button of a shirt that must be put right, in order for the China-US relationship to truly stabilise, improve and move forward," Xi said.
Earlier, Wang told Blinken that the "giant ship" of the China-US ties had stabilised, "but negative factors in the relationship are still increasing and building".
Foreign Minister Wang Yi says the US-China relationship "is facing all kinds of disruptions". (AP PHOTO)
Wang also said the US had taken "endless" measures to suppress China's economy, trade, science and technology, equating such steps to containment.
"And the relationship is facing all kinds of disruptions," Wang told Blinken.
"China's legitimate development rights have been unreasonably suppressed and our core interests are facing challenges."
The agenda for the talks was set during the November summit between Biden and Xi in San Francisco and a follow-up call in April.
Underscoring the growing discord between the two sides, hours before Blinken landed in China on Wednesday, President Joe Biden signed a bill that included $US8 billion ($A12 billion) to counter China's military might as well as billions in defence aid for Taiwan and $US61 billion ($A94 billion) for Ukraine.
Wang said the US must not step on "red lines" covering sovereignty, security and development interests - an apparent reference to Taiwan, the democratically governed island that China claims as its own, and the disputed South China Sea.
Other issues being discussed include artificial intelligence and the US push for progress on the curbing of China's supply of the chemicals used to make fentanyl.
Blinken, along with senior US officials focused on anti-narcotics collaboration with China, met China's minister of public security, Wang Xiaohong, to discuss the fentanyl issue.
Blinken told the news conference that China has made some progress on the issue, but said that "more needs to be done".
The two countries also agreed to hold their first talks on artificial intelligence in the coming weeks, he said.