HIV was the third leading cause of natural deaths in South Africa in 2013, up three places from the previous year, and the second highest killer of young people, a survey by the national statistics agency showed on Tuesday.

The survey, based on 458,933 deaths that occurred in 2013, showed that HIV was responsible for 11 percent of deaths in the 15 to 44 age group, Statistics South Africa said.

Despite having one of the most extensive HIV/AIDS treatment programs in the world, including rolling out free anti-retroviral drugs a decade ago, the rate of new infections in South Africa has increased.

Over six million South Africans, or 18 percent of the population, are currently infected with the disease, according to the United Nations.

This has left Africa's most advanced economy with the highest number of people living with the disease in the world.