Blinken has publicly warned for weeks that China is considering Russian requests for weapons to fight in Ukraine, with some reports indicating limited shipments by Chinese companies to Moscow.

"As we speak today, we have not seen them cross that line," America's top diplomat said in response to a question at a Senate committee on whether China was providing "lethal aid" to Russia.

President Xi Jinping this week paid a visit to Moscow in which he pushed a Chinese proposal for a ceasefire in the war -- a call met with skepticism by Washington, which fears Russia would use a pause to regroup battered forces on the ground.

"I think their diplomatic support, their political support, and to some extent material support for Russia certainly goes against our interest in bringing this war to an end," Blinken said of China.

He also said the United States would encourage other countries to extradite Russian President Vladimir Putin if he visits following an arrest warrant issued recently by the International Criminal Court.

"I think that anyone who is a party to the court and has obligations should fulfill their obligations," Blinken said.

But he stopped short of saying the United States would do so itself.

"I have to look at the laws and, as you know, we're not actually a party to the ICC, so I don't want to engage in that hypothetical," Blinken said.

"I don't think he has any plans to travel here soon," he said of Putin.

Blinken was responding to questions from Republican Senator Lindsey Graham who said the United States should arrest Putin and extradite him to The Hague if he steps on US soil.

The United States has historically been hostile to the ICC, with the previous Republican administration of Donald Trump imposing sanctions on the court's then-prosecutor for probing US military actions in Afghanistan.

President Joe Biden after taking over has improved relations with the court and dropped the sanctions, although a 2002 US law prevents the United States from formally assisting the court.

Putin has not visited the United States since 2015 when he attended the United Nations General Assembly in New York.

Russia is part of the Asia-Pacific Economic Cooperation forum, which holds its summit in November in San Francisco, but it is highly unlikely the United States would invite Putin.