"This oral test provides another important option for people who might be afraid of a blood test," Health and Human Services Secretary Tommy Thompson told a press conference launching the marketing of OraSure Technologies' test called OraQuick.

"It will improve care for these people and improve the public health as well," he said.

The Centers for Disease Control estimates one million Americans are infected with the HIV virus and do not know it.

OraQuick, which the FDA says is 99% accurate, provides results in about 20 minutes, detecting antibodies produced by the subject in reaction to an infection by one of the two strains of the virus that cause AIDS.

The Bethlehem, Pennsylvania-based manufacturer's stock jumped 20% on the New York stock market with the FDA announcement.

Mouth swab

The new test, which must be administered by a health professional, analyses a sample of cells swabbed from the subject's mouth.

Once the sample is taken, the swab is inserted in a small testing device with a window that signals a positive or negative result.

In the case of a positive result, a blood test is mandatory.