The close of 2007 witnessed almost 3 million people in developing nations receiving anti-retroviral (ART) treatment, but nearly twice that number still require life-saving medicines, a United Nations study said.

Almost one-third of the estimated 9.7 million people in need of ART received it by the end of 2007, leaving nearly 7 million without access, The study report, entitled "Towards Universal Access: Scaling Up Priority HIV/AIDS Interventions in the Health Sector," added.

Among the obstacles to treatment cited by the study are poor patient retention rates and large numbers of people unaware of their HIV status.

Tuberculosis is one of the leading causes of death among those living with HIV, and the number one cause in Africa, according to the study.

Currently, HIV and tuberculosis treatments are not sufficiently integrated, and many die as a result of not being able to access medicines to treat both diseases, the report warned.

The study also pointed to other progress like improved access to interventions to prevent mother-to-child HIV transmission, increased testing and counseling and stepped up commitment to male circumcision in heavily-affected areas in sub-Saharan Africa.