China, wary of the troubled US economy, has already "cancelled America's credit card" by cutting down purchases of debt, a US congressman said on Thursday.
China has the world's largest foreign reserves, believed to be mostly in dollars, along with around $800bn in US Treasury bonds, more than any other country.
But Treasury Department data shows that investors in China have sharply curtailed their purchases of bonds in January and February.
Representative Mark Kirk, a member of the House Appropriations Committee and co-chair of a group of lawmakers promoting relations with Beijing, said China had "very legitimate" concerns about its investments.
"It would appear, quietly and with deference and politeness, that China has canceled America's credit card," Kirk told the Committee of 100, a Chinese-American group.
"I'm not sure too many people on Capitol Hill realise that this is now happening," he said.
The Republican lawmaker said that China was justified in concerns about returns from finance giants Fannie Mae and Freddie Mac, which were bailed out by the US government due to the financial crisis.
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