Despite government-administered tests in recent days showing that more than 100 people in Battambang have been infected with HIV, Prime Minister Hun Sen said yesterday that he was “99 per cent” sure the results are wrong.

Speaking at a graduation ceremony yesterday, the premier said he does not believe HIV infections have occurred.

“Right now, 99 per cent, I don’t believe it’s AIDS,” he said, referring to the disease that develops from HIV infection. “They might have a virus, but it’s not AIDS.… Can an 80-year-old person get AIDS? And can young people who do not know anything get AIDS?”

A 74-year-old man tested positive for HIV in Roka village in late November. Since then, testing and retesting has ramped up – with the National AIDS Authority (NAA) and other groups rushing to the area – and at least 106 people have now registered positive readings, according to the NAA.

Villagers have accused Yem Chroeum, an allegedly unlicensed doctor, of administering injections to at least 30 people to treat various complaints.

Chet Vanny, deputy provincial police chief, yesterday alleged that police had found used and unused needles mixed together while searching Chroeum’s house.

“The doctor is at the police station clarifying some things. We have not taken any action against him,” he said.

In his speech, Hun Sen urged people not to jump to conclusions about the situation and instead use “all scientific possibilities” to determine what had happened.

But he also questioned the testing method his own authorities were using to determine whether villagers in Sangke district were HIV-positive.

“If we bring this machine here, half of us might also find out we have AIDS,” he said. “Actually, we don’t look down on our doctors or [health] equipment. But it’s hard to believe.”

Health agencies yesterday, however, confirmed that they were dealing with HIV.

In a statement headlined “HIV cases in Sangke district, Battambang”, the Ministry of Health, the World Health Organization (WHO), UNAIDS, Unicef, the Pasteur Institute in Cambodia, and the US Centers for Disease Control and Prevention say they are investigating an “outbreak”.

“A complete investigation into this outbreak will be carried out with full technical assistance given,” Health Minister Mam Bunheng said in the statement.

But Hun Sen wasn’t the only one casting doubt over the tests yesterday.

“We cannot say that they are positive [readings],” said Dr Mean Chhi Vun, director of the National Centre for HIV/AIDS, Dermatology and STDs (NCHADS). “They are reactive results, not positive. More tests are needed.”

Asked to explain what percentage of people in the world whose blood sample produced a “reactive” reading were later found to have HIV, Chhivun said he did not know.

Marie-Odile Emond, UNAIDS country director, however, said that it was “definitely HIV” that officials were dealing with.

“There have been a number of cases confirmed,” she said.

Dr Didier Fontenille, from the Pasteur Institute of Cambodia, said his laboratory was providing additional testing of blood samples to confirm positive readings. Of the 30 so far retested by the institute, all were positive, Fontenille said. They were still waiting on additional test results last night.

“It is without doubt,” he said of those confirmed. “It is definitive … the [Health Ministry’s] tests were well-done.”

Chroeum remained in custody yesterday, though no charges have been laid and his family said he was being kept away from his village in Roka commune to protect his safety.

James McCabe, director of operations at the Child Protection Unit, said the doctor in question was continuing to “assist police with inquiries”.

Investigators, he added, spent hours yesterday searching a house, where syringes, vials and medicines were seized.

Chhem Choeun, 32, Chroeum’s son-in-law, said he was cooperating with police while they searched his family home.

“My dad has been at the police station for two days,” he said. “He has not said anything. Police fear for his safety, so they are not letting him go home.”

McCabe said authorities had widened their investigation to encompass as many as five communes, he said.

“We have to consider every possibility. Everything has to be discounted. Every single person will need to be retested and thoroughly interviewed.”

It could be months before the investigators deliver a finding, he added.

Some experts yesterday said they had never heard of such a case happening before and questioned whether one doctor could be responsible.

“This is a totally new situation and I don’t recall having encountered similar incidences like this in the past,” said Dr Masami Fujita, the WHO’s HIV/AIDS team leader in Cambodia. “What makes it worse is that there are so many unknowns,” Fujita said. “We’re looking at other possibilities at this point.”

Sarah Hand, chief executive of international HIV/AIDS charity AVERT, said it was “virtually impossible” for more than 100 HIV-positive patients to contract the virus from a single doctor.

“It doesn’t mean that if some individuals were injected with contaminated blood that every single person treated would get the virus,” Hand said. “HIV remains a relatively hard virus to contract … so it’s very unlikely that the contamination came from just one source.”

Harun Rashid, regional head of the Malaysia-based Coordination of Action Research on AIDS and Mobility, said that the incident was a “failure in the Cambodian government’s and global community’s job in educating locals about HIV/AIDS”.

“The doctor, even if he’s unlicensed, must have gotten these needles somewhere, and those places should be investigated,” Rashid said.

Some in the government, meanwhile, were in damage-control mode yesterday.

“Please trust our health system,” said Bunheng, vowing sweeping changes “What is necessary is medical equipment, which the government will supply.”

Chhi Vun, from NCHADS, said those infected would receive free antiretroviral drugs for the rest of their lives.

More villagers yesterday were linking their infections to recent doctor trips they had made.

Bunna Sambath, 19, said he believed an injection he had six months ago when he was battling dengue may have been the time that he contracted HIV.

“I am not ashamed, because I have done nothing wrong, and I am not the AIDS carrier alone – almost the whole village is,” he said.

ADDITIONAL REPORTING BY SHANE WORRELL AND SARAH TAGUIAM