Phat Sarath, 37, was arrested on Thursday after his wife informed police she had walked in on her husband having sex with the 15-year-old girl, said Mr Ngan Sary, a district police chief of Takeo province in southern Cambodia.

Phat Sarath and his wife are both HIV-positive and have been receiving life-prolonging treatment at the local center, which provides care for HIV-Aids patients and also houses orphans, he said. Takeo province is 65 kilometres south of capital, Phnom Penh.

The girl was an orphan who lived at the center. Phat Sarath is accused of having paid her 5,000 riel (S$1.87) on three occasions in October to have sex with him, the policeman said.

'He knows that he is HIV-positive and still had sex with the girl without using a condom. His act is unforgivable', Mr Ngan Sary said. He could face up to 30 years in prison.

Under a Cambodian law on HIV/Aids prevention and control, the man could face 10 to 15 years in prison for having unprotected sex while knowingly infected with the HIV virus.

Sex with a minor under age 18 carries a sentence of up to 15 years, Mr Ngan Sary said. The man has not been formally charged.

In 2006, an HIV-positive Cambodian man was sentenced to 10 years in prison for intentionally trying to infect his wife with the virus that causes Aids. -- AP