A report release jointly by WHO, UNAIDS and UNICEF said about 31 percent of the estimated 9.7 million people in need of anti-retroviral therapy received it by the end of 2007, although an estimated 6.7 million in need are still unable to get the life-saving drugs.

"This report highlights what can be achieved despite the many constraints that countries face and is a real step forward towards universal access to HIV prevention, treatment care and support," Dr. Peter Piot, executive director of UNAIDS, said in a statement. "Building on this, countries and the international community must now also work together to strengthen both prevention and treatment efforts."

The authors warned that further access to the drugs will likely be slowed by weak health systems in the worst-affected countries. They said it is difficult to train and retain health-care workers because of the migration of skilled health-care personnel, as well as the high mortality rates from HIV.