In early May, a mass poisoning event in Chetr Borei district in the Cambodian province of Kratie killed at least 13 people and caused acute levels of sickness for up to 300 more.

An investigation led by Cambodia’s Minister of Industry and Handicraft Cham Prasidh revealed high levels of cyanide in a nearby river, which is the source of drinking water for communities in the region that were affected by poisoning. However, Prime Minister Hun Sen dismissed the claim, saying the poisoning was caused by rice wine and agricultural chemicals.

The Chetr Borei incident was reportedly followed by another mass poisoning of 80 Phnorng indigenous peoples in neighboring Mondulkiri. A resident interviewed for the report claimed that mining operations drilling upstream near the area’s water source was to blame.

In July, another poisoning incident was reported in which three people died and sixty others were hospitalized in Snuol, Kratie Province. Rice wine was again officially blamed as the cause.

A spate of mass toxic poisonings in the Cambodian provinces of Kratie and Mondulkiri have hospitalized hundreds and killed at least 16 people since May. Although the causes of the three events are as yet unproven, some suspect it may be due to cyanide from gold mining as high levels of the compound have been found in rivers used by affected communities.

Despite growing public alarm and unanswered questions, the Cambodian government has issued a license for yet another international mining company to operate in the area, as part of a policy to rapidly expand industry presence in the Southeast Asian country.

Problems began in early May when a mass poisoning in Chetr Borei district in the Cambodian province of Kratie killed at least 13 people and caused acute levels of sickness for up to 300 more.

An announcement from Minister of Industry and Handicraft Cham Prasidh that cyanide had been detected at high levels in rivers known to be water sources for affected communities sparked a rare display of public disagreement in the ruling regime, with Prime Minister Hun Sen stepping in to slap down Prasidh and dismissing his statements. Cyanide is increasingly widely used in the largely unregulated Cambodian gold mining industry.

After the poisoning, Prasidh said he and his team investigated mining sites and conducted water analysis.

“As for the Te River, when we started analyzing the water along the river in Mondulkiri province, we found very, very high concentrations of cyanide,” Prasidh said in a video shortly after the poisoning.

“They used it without a protection system and when it rained, the pool that stored the cyanide substance overflowed into the stream and caused poisoning,” Prasidh said, as reported May 21 by the Khmer Times.

“So we then looked for the source, all the way to Mondulkiri province, as the Te river originates in Mondulkiri. And we started finding it [cyanide] in some sites where gold mining and prospecting is taking place, some with a license, others without one, and we even saw cyanide tanks,” he said.

However his remarks were quickly dismissed by Prime Minister Hun Sen, a move supported by the Ministry of Mines and Energy.

“Why did you need to elaborate on this issue without my knowledge?” Hun Sen said, according to a May 25 story by Radio Free Asia. “Your comments caused some controversy among your fellow ministers in other government departments, and this is because you spoke to the media before clearing your report with me.”

“I have removed ministers from the government before for doing this,” Hun Sen reportedly said.

In a 20-minute address to the council of ministers, 24 May, Prime Minister Hun Sun dismissed cyanide as the cause and instead blamed it on a cocktail of methanol from badly made rice wine and agri-chemicals. His views were supported by others in the Ministry of Health.

“A small incident like this shouldn’t be giving the PM this much of a headache,” Hun Sen said during his speech, apparently dismissing the severity of the incident.

“The situation smacks of a cover-up,” said director of Mother Nature Cambodia, Alejandro Gonzalez-Davidson. He is demanding an independent investigation of the incident. He told Mongabay the bodies of the deceased have been cremated without an autopsy and the results of blood tests in Singapore, which the government said had low levels of cyanide, have not been made public.

With limited evidence to go on, the cause of the poisoning is hotly contested. There are commonalities to the symptoms suffered by poison victims, which, according to a translated press release issued May 8 pain, loss of energy, fatigue, dizziness, difficulty in breathing.”

These match symptoms common to both cyanide and methanol poisoning, making it hard to distinguish the cause.

“The Cambodian people have finally woken up to that fact that gold mining, as it is conducted in Cambodia, can be a killer. It can be a major health hazard especially in remote areas, and a major source of environmental destruction,” Gonzalez-Davidson said.

The promise of gold has attracted artisanal small-scale miners to the region where they compete for space with industrial scale mines that have been awarded government permits. Conflict has broken out when mining companies and authorities have reportedly tried to stop their operations.

On July 10th Emerald Resources NL, an Australia-based gold mining company, announced that its mining licence for the Okvau Gold Project had been granted by the Cambodian Ministry of Mines & Energy.

In a media release, managing director Morgan Hart underlined the Cambodian government’s commitment to expanding the gold-mining sector despite potential risks, saying, “the Okvau Gold Project development has received strong endorsement from the Cambodian Prime Minister following the Royal Government’s diligent approach to the environmental permitting allowing for the grant of the Mining License for the Okvau Gold Project.”

The Australian Renaissance minerals (Cambodia) Limited mine, a joint venture with Emerald Resources NL, says it is currently preparing to begin commercial operations later this year. Its annual report states the two plan to merge to exploit the “Okvau and adjoining O’Chhung exploration licences covering approximately 400km2 of project area.”

According to a 2016 project prospectus, Emerald Resources is planning sediment control ponds to dam sediment from the tailings storage facility and prevent it flowing into the Prek Te River – a primary source suspected for the May mass poisoning. These dams play a critical role at containing the toxic waste and preventing similar catastrophes in future.

The project site is also located within a protected area, which is attracting concern from the conservation community.

“The Okvau Deposit is located outside the Core Zone of the Phnom Prich Wildlife Sanctuary but within the outer boundaries of that sanctuary,” states the Renaissance Minerals 2016 Financial Report.

Concerns have been raised in the Cambodian media about the potential impact of gold mining on wildlife in the region, especially in protected areas.

“The Phnom Prich Wildlife Sanctuary (PPWS) covers an area of more than 2,000km², located within the heart of the Eastern Plains Landscape (EPL),” according to WWF Cambodia. A biodiversity hotspot it, “hosts an impressive array of wildlife species and rich habitat diversity, including 18 endangered and critically endangered species (mammals, birds and reptiles).” These include species like the Asian elephant (Elephas maximus), leopard (Panthera pardus) and banteng (Bos javanicus).

Mongabay sought comment from Emerald Resources and the Cambodian government, but received no reply by press time.

Other international companies have reportedly also joined the gold rush. Adjacent to the Renaissance prospect is the Chinese-owned Rong Cheng Industrial Investment (Cambodia) Co., Ltd mine. According to the Phnom Penh Post, the company is already undergoing exploration operations. This mine was investigated by Prasidh and his team as a possible cause of the poisonings, allegations that Rong Cheng representatives have denied in media reports. The full results of that investigation have not been made public.

The Kratie incident was shortly followed by another mass poisoning of 80 Phnorng indigenous peoples in neighboring Mondulkiri, as reported by Radio Free Asia. A resident interviewed for the report claimed that mining operations drilling upstream near the area’s water source was to blame.

In July, another poisoning incident was reported in which three people died and sixty others were hospitalized in Snuol, Kratie Province, according to the Phnom Penh Post. Rice wine was again officially blamed as the cause, though one Cambodian activist (who asked not to be named) noted on Facebook, that, “children who don’t drink rice wine were also poisoned.”

While the poisonings are raising widespread concern, the Cambodian government has so far refused to release its findings from tests, and appears to remains steadfast against growing demands for an independent investigation.