Unhealthy sexual behavior is the biggest culprit in spreading HIV/AIDS on the mainland, while men who have sex with men (MSM) are now the most likely to become infected by the disease, an official with the Ministry of Health said yesterday.

"In the past, between 1 and 3 percent of MSM in the mainland had HIV/AIDS. Now it is anywhere from 2.5 to 6.5 percent," Hao Yang, deputy chief of the disease prevention and control bureau under the Ministry of Health, said.

More than half of China's MSM have more than one sexual partner, but only between 10 and 20 percent of them use condoms, he said.