"Some leaders have buried themselves in the illusion that HIV/AIDS is not really an Asian problem - that the infection will somehow restrict itself to the high-risk groups," Nafis Sadik told a UN conference on health and poverty.
"This is a denial of reality," she told the meeting, attended by ministers and officials from 47 Asia-Pacific countries. "Countries must tackle it head on."
Sadik, special UN envoy for HIV/AIDS in Asia, did not identify which Asian leaders she thought were not facing up to the AIDS threat.
While infection rates are far lower than in southern Africa, the global epicentre of the disease, experts say the Asia-Pacific region may account for 40% of new global infections by 2010, if prevention efforts are not stepped up.
Adult HIV prevalence rates are still relatively low in Asia, exceeding one percent in only three countries - Cambodia, Thailand and Myanmar, according to the World Health Organisation.
But the region added one million new cases last year. "Every day HIV spreads across various sub-populations and into the general population," Sadik said.
The pandemic had yet to show its "full power for destruction" in Asia, but African countries had seen the full, appalling impact, Sadik said.
"Some leaders have buried themselves in the illusion that HIV/AIDS is not really an Asian problem"
Nafis Sadik, special envoy, United Nations
"Two of the most advanced countries in that region, Botswana and South Africa, are looking at the possibility of economic disaster and social disintegration as a result of HIV/AIDS," Sadik told the annual meeting of the United Nations Economic and Social Commission for Asia and the Pacific (ESCAP) in Bangkok.
An estimated 14 million people are affected by AIDS in southern Africa. South Africa has the world's highest caseload with 4.7 million people infected with HIV or AIDS, while the disease affects about 35% of the population of Botswana.
Among Asia's most populous countries, about one million people are living with HIV in China, and that could rise to 10 million cases by 2010.
Beijing has been slow in responding to the pandemic and only in recent years felt able to discuss sexual health in public.
India could have up to 25 million HIV carriers by 2010, up from nearly four million cases today. HIV has also shown up in 26 of Indonesia's 30 provinces, Sadik said.
Thailand, where infection rates are falling after a campaign to promote condoms in the commercial sex trade, is one of the region's rare success stories.