As many as 10,000 college students fought with Chinese police in four days of protests over their academic status, damaging cars and buildings and leaving at least 20 people injured, a foreign monitoring group said Thursday.

The protests erupted Oct. 21 in Nanchang, a city in Jiangxi province, after students learned that records from two private institutions might not be recognized by the government, the Hong Kong-based Information Center for Human Rights and Democracy said.

The paramilitary People's Armed Police was deployed to contain the protests and at least five people were detained, the report said. It said the protesters were ethnic minorities, including some 2,000 Uighurs from China's Muslim northwest. The report said students were calling for a protest march to be held on Sunday.

People who answered the phone at the Nanchang police headquarters and the administration offices of the two schools wouldn't confirm the report or give their names.

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China has seen a series of such protests over the status of degrees granted to students who study at private schools set up as profit-making ventures by universities. The schools serve students who failed intensely competitive entrance exams for government-subsidized universities but can afford to pay higher private tuitions.

Universities initially granted such students degrees and academic records in the name of the parent institution. But the government has cracked down on that practice, prompting student complaints that the new status hurts their job prospects.

The institutions that were targeted in the Nanchang protest were the Jiangxi Ganjiang Institute of Technology and the Jiangxi Institute of Fashion College, according to the Information Center.