The first ever over-the-counter home HIV test is expected to go on sale in the US within months, after securing regulatory approval.

The 'OraQuick' test checks saliva from a mouth-swab for HIV and can produce results in 20 to 40 minutes.

It is a home-use version of a test that has been used by medical professionals and others trained to screen for HIV for the past eight years.

Official estimates suggest 1.2 million people in the US are HIV-positive, but that 20% of them are not aware they are infected.

US Food and Drug Administration officials said the test is aimed at people who might not otherwise get tested.

HIV awareness groups hailed the approval as an important step in expanding testing for the virus.

The FDA previously approved several HIV test kits designed to be used at home, although those kits - which usually require a blood sample - must be sent to a laboratory to be developed.

FDA stressed in its approval announcement that the test is not 100% accurate.

A trial conducted by Orasure showed the home test correctly detected HIV in those carrying the virus only 92% of the time. That means the test could miss one person for every 12 HIV-infected people who use the kit.

The test was accurate 99% in ruling out HIV in patients not carrying the virus. That means the test would incorrectly identify one patient as having HIV for every 5,000 HIV-negative people tested.

Orasure has marketed a version of OraQuick to doctors, nurses and other health care practitioners since 2002.

When used by professionals, the test is shown to accurately identify both carriers and non-carriers 99% of the time.

While it is not clear why the test appears less accurate in consumer trials, company researchers said they expected the test's specificity to drop when used by consumers versus professionals.

Orasure plans to launch the test in October, selling it through retailers and online pharmacies.