David Cooper, the co-chairman of an International AIDS Society (IAS) conference to be held in Sydney from July 22-25, said research on male circumcision represented a major development in HIV prevention.

"We always knew that if you went into any particular African country that HIV rates among Muslim men were lots lower," Cooper told AFP.

"But we were never sure that the Muslim men had lower numbers of partners than non-Muslim men, so people always doubted it."

Cooper said the only way to ensure the link between lower HIV rates and circumcision was not due to cultural factors was to carry out random trials, the results of which will be presented at the Sydney conference.

He said three trials were conducted in South Africa, Kenya and Uganda, each involving more than 2,000 heterosexual men, half of whom were circumcised.

"The reduction in HIV infection was about 60 percent, so clearly it works," said Cooper, who is also the director of Australia's National Centre for HIV Epidemiology and Clinical Research.

Cooper said the studies showed circumcision could be a powerful tool in helping curb HIV infection in sub-Saharan Africa, where infection rates in some countries are up to 40 percent of the adult population.