The infected cases have surpassed 100 and is believed to have been spread by contaminated needles used by an unlicensed doctor, reported local media.
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More than 800 panicked residents of Rokar village have sought testing after reports of infections emerged last week. Some 106 people have tested positive for HIV said the National AIDS authority.
"I call for a thorough investigation into the issue," Hun Sen said in a televised speech on Thursday.
The Ministry of Health, the World Health Organization and UNAIDS have sent teams to the village to carry out more investigations and to provide free testing and treatment services.
"I urge everyone to stay calm and avoid listening to or spreading rumors," said Dr. Mam Bunheng, minister of health in a press release.
"We should also all fully respect the privacy of the affected families and ensure they do not face stigma and discrimination," he added.
Villagers are accusing an allegedly unlicensed local doctor for using contaminated needles, reported Phnom Penh Post. He now remains in protective custody by the police.
UNAIDS estimates there are 76,000 people living with HIV in Cambodia. The country has been widely praised for its progress in tackling AIDS. New HIV infections have dropped by 67% from 3500 in 2005 to 1300 in 2013, according to UNAIDS.
Prime Minister Hun Sen announced last week that Cambodia is committed to stopping new HIV infections by 2020. The government will allocate US$ 3.7 million of national funding to HIV treatment from 2015 to 2017.