The epidemic will worsen dramatically in coming years unless there is better education and stronger political will to combat the disease, warned Massimo Ghidinelli, the World Health Organization's regional adviser on HIV/AIDS.
His comments came at a news conference after a seminar in Hong Kong at which regional AIDS experts discussed the growing trend.
Asia is believed to have the world's largest number of men who have sex with other men, with a preliminary estimate of 10 million, according to WHO.
While describing the figure as "extraordinary high," Ghidinelli said it still appeared to be conservative because of the stigmatization of male-to-male sex.
WHO said fragmentary information from the region indicated a rapid spread of HIV among gay and bisexual men, but that full data weren't available. The seminar was called to strengthen efforts to study and address the problem, it said.
Ghidinelli said low condom use among younger men in male-to-male relationships was fueling the transmission of HIV.
"Younger men engaging in sex with men are entering into a sexual arena without the same level of awareness and without taking the same level of protection that the older generation was taking," Ghidinelli told a news conference.
Ghidinelli said the AIDS experts agreed at the conference to set up a regional task force to collect information on male-to-male transmission and to strengthen measures to fight the disease.