The number of Chinese students infected with HIV increased by 24.5 percent year-on-year in 2012, and sex between men was the main cause of the new infections, a senior health expert said.

There were 1,700 students infected with HIV last year, Yu Jingjin, director of the bureau of disease control and prevention under the National Health and Family Planning Commission, was quoted by Xinhua News Agency as saying on Saturday.

Yu said 64.8 percent contracted the virus through sex with people of the same gender. Eighty-seven percent of HIV cases were sexually transmitted.