More than 80 students from the University of Hong Kong and University of Macao are missing in northwest China's Qinghai Province, sources with local public security department said on Thursday night.

An unnamed official with Qinghai Provincial Public Security Department said contact with the students, who were majoring in geology, was lost in Menyuan Hui Autonomous County, Haibei Tibetan Autonomous Prefecture in Qinghai.

Local public security officials have begun a search operation.

No other information is immediately available.

(Xinhua News Agency July 17, 2009)