WASHINGTON (Reuters) - Circumcising men cuts their risk of being infected with the AIDS virus in half, and could prevent hundreds of thousands or even millions of new infections, researchers said on Wednesday.

Circumcising men worked so well that the researchers stopped two large clinical trials in Kenya and Uganda to announce the results, although they cautioned that the procedure does not make men immune to the virus.

Public health leaders hailed the results as pointing to a potentially powerful way to reduce HIV infections in Africa, the continent hardest hit by AIDS.

"It does have the potential to prevent many tens of thousands, many hundreds of thousands and perhaps millions of infections over coming years," Dr. Kevin De Cock, director of the World Health Organization's Department of HIV/AIDS, told reporters.

A U.S. National Institutes of Health study in Kisumu, Kenya, involving 2,784 men aged 18 to 24 showed a 53 percent reduction of HIV infections in circumcised men compared to uncircumcised men. A parallel study involving 4,996 men aged 15 to 49 in Rakai, Uganda, showed circumcised men were 48 percent less likely than uncircumcised men to become infected...