Almost 60 million people have been infected by HIV and 25 million people killed by causes related to the virus since the epidemic started, according to new data published by UNAIDS on Tuesday.
While prevention programmes have helped to cut infection rates by 17 percent over the past eight years, the total number of people living with HIV continued to rise in 2008.
By the end of 2008, a total of 33.4 million people or 20 percent more people were living with the epidemic compared to in 2000. The UN figures
"The continuing rise in the population of people living with HIV reflects the combined effects of continued high rates of new HIV infections and the beneficial impact of antiretroviral therapy," said UNAIDS in its annual report.
Sub-Saharan Africa remains the most affected region, as it is home to 67 percent - 22.4 million - of those currently living with the human immunodeficiency virus.
In South and South-east Asia, 3.8 million people are now living with the infection, added UNAIDS.
The comparative figure for Eastern Europe and Central Asia is 1.5 million.
UNAIDS observed that in these regions, the epidemic was "experiencing significant transitions."
While Asia's epidemic was once concentrated among risk groups such as sex worker, drug users and homosexuals, it is now "steadily expanding into low-risk populations to the sexual partners of those most at risk."
In Eastern Europe and Central Asia, the epidemic was once characterized mainly by transmission through drug users, but it is now increasingly moving into "significant sexual transmission."