SYDNEY, Australia (AP):

New HIV cases in Australia surged more than 40 per cent from 2000 to 2005, according to study results released yesterday, prompting fears that drug treatment advances are making people lax about practising safe sex.

The annual survey report, issued by the National Center in HIV Epidemiology and Clinical Research, found that new HIV infections reported in Australia rose from 656 in 2000 to 930 in 2005 - a 41 per cent leap. HIV is the virus that causes AIDS.

Gay men accounted for about 70 per cent of the new cases. Heterosexuals made up 19 per cent, while intravenous drug users and unknown transmission paths accounted for the rest.

According to the report, new infections hit an all-time high of about 1,700 in 1984, then declined steadily through the late 1990s. But in 2000, the trend apparently reversed.

It's not just HIV that is on the rise in Australia.

Around 41,300 new cases of the sexually transmitted disease chlamydia were reported in 2005, a fourfold increase over 1995.

New gonorrhoea cases have almost doubled in the past decade, the study said.

"It's very possible that people are just not prioritising safe sex as they maybe used to in the very serious HIV/AIDS era" of the late 1980s and early 90s, said the centre's deputy director, John Kaldor.

"It might be here that improvements in HIV treatments have lessened the motivation for people to protect themselves sexually," Kaldor said.

Australia has about 15,000 people living with HIV, and around 70 per cent are being treated with life-prolonging anti-retroviral drugs, the study found.

Don Baxter, executive director of the Australia Federation of AIDS Organisations, said widespread use of the drugs _ which have been found to slow the progression of HIV to AIDS _ could be a factor behind the recent rise, especially among gay men.