But, some are worried the move will confuse people that HIV can be transmitted through saliva.

The National AIDS Commission allowed the tests to be used in hospitals only and administered by doctors only. The tests may not be sold over the counter in pharmacies, Public Health Minister Mongkol na Songkhla said.

The tests can be administered to those who agree to them and subjects must undergo consultations before and after testing.

Tests results are confidential.

Blood tests have been the sole method of determining HIV infection until now. Mongkol said the saliva test had been prohibited since 1994 but as a result of improved accuracy the commission approved the faster exam for professional use.

"But, I must stress the test checks for HIV antibodies only; you can rest assured HIV/Aids cannot be contracted through saliva," Mongkol said.

He added it would make it easier for more people to take HIV tests and allow infections to be treated sooner.

The ministry will issue a regulation controlling the use of saliva tests.

Thai Network of People Living with HIV/Aids president Virat Phurahong said the advantage of the saliva test was its ease of use and pain-free application when compared with blood tests.

But, people must be educated that HIV cannot be contracted through saliva, Virat said.

"We must realise many people still don't understand how HIV/Aids is and is not transmitted," Virat said.

Meanwhile, Disease Control Department chief Dr Thawat Suntrajarn asserted drugs and pornography were increasing teenagers' risk of contracting HIV/Aids.

In a survey of 14-year-olds, 3 per cent of the boys said they had had sex and just half used condoms. The group admitted it used narcotics or alcohol before sex.

Of the 2 per cent of the girls surveyed who said they had lost their virginity, more than 70 per cent did not use condoms.