Hundreds and possibly millions of new HIV infections could be prevented if men are circumcised, according to experts.

It comes after scientist were so stunned at the success of two large clinical trials in Kenya and Uganda, where men had the procedure, that the studies were stopped early.

HIV sufferer Mbulelo Makaula

But researchers warned that circumcision does not make men immune to the virus which causes Aids.

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

Experts say the reduced HIV risk may be because cells on the inside of the foreskin are particularly susceptible to HIV infection.

The virus may also survive better in a warm, wet environment like that found beneath a foreskin.

A study in Kisumu, Kenya, involving 2,784 men aged 18-24, showed a 53% reduction of HIV infections in circumcised men

A parallel study, involving 4,996 men aged 15-49 in Rakai, Uganda, showed circumcised men were 48% less likely than uncircumcised men to become infected.

The trials began in 2005 and were due to go on until mid-2007.

The World Health Organisation said: "It does have the potential to prevent many tens of thousands, many hundreds of thousands and perhaps millions of infections over coming years."