China has called on the United States to protect the rights of foreign students after US Secretary of State Marco Rubio ordered a suspension of student visa processing amid a crackdown on universities.

"We urge the US side to earnestly safeguard the legitimate rights and interests of international students, including those from China," Foreign Ministry spokeswoman Mao Ning told a regular news conference on Wednesday.

A cable signed by Rubio and seen by AFP orders embassies and consulates not to allow "any additional student or exchange visa... appointment capacity until further guidance is issued."

The government plans to ramp up vetting of the social media profiles of international applicants to US universities, the cable said.

The New York Times reported that the suspension of interviews with visa applicants was temporary.

Rubio earlier rescinded hundreds of visas and President Donald Trump's administration has moved to bar Harvard University from admitting non-Americans.

The suspension of student visa processing came as the Trump administration seeks unprecedented control of the nation's universities by slashing funding and curbing international enrollment. It is the latest escalation in the White House's crackdown on foreign students, which has seen it revoke visas and deport some of those involved in protests against the war in Gaza. (AFP)