Most people think their faithfulness could protect them against HIV, a survey has found, marking a triumph in safe sex campaigns in South Africa.

"The survey showed that faithfulness had gone up as a way to prevent HIV," said Dr Saul Johnson, managing director for Health and Development Africa, at a media briefing in Johannesburg on Monday.

The percentage of respondents who believed faithfulness was a way to prevent HIV had increased from 26 percent in 2006 to 39.1 percent in 2009.

The popularity of safe sex using a condom was not mentioned.

The Second National HIV/Aids 2009 survey was conducted in all nine provinces between June and August last year.

A total of 9728 people aged between 16 and 55 took part in the survey, which involved completing in-depth, structured questionnaires in face-to-face interviews.