The founder of a Cambodian conservation group that saw three of its activists jailed this month says the government is taking aim at them for their work exposing corruption and environmental abuse - an allegation the government denies.
The arrests mark at least the third time that Mother Nature Cambodia's activists have faced criminal charges.
Six of its Cambodian members are jailed and two others have been convicted in absentia.
The group's Spanish founder, Alejandro Gonzalez-Davidson, who was deported from Cambodia in 2015, says the latest charges are aimed at silencing the group's documentation of environmental exploitation and naming officials they say are corrupt.
"It's not about legal issues. It's about a regime which is paranoid, and it's unpopular," Gonzalez-Davidson said in a video call with Reuters.
"They basically are just trying to send this message to the rest of the population, scare them into silence," he said.
Interior Ministry spokesman Khieu Sopheak denied Mother Nature is being targeted because of its environmental work, saying the group is plotting to overthrow the government of longtime leader Prime Minister Hun Sen.
"They are seen as doing work protecting the environment, but that's not their honest work," Khieu Sopheak said. "Their objective is to rebel against the government, using means that are not through elections."
In the latest arrests, Mother Nature's activists Sun Ratha, 26; Ly Chandaravuth, 22; and Yim Leanghy, 32, were detained on June 16 while documenting suspected pollution runoff into the Tonle Sap river in Phnom Penh.
They were charged with plotting against the government and with insulting Cambodia's king along with Gonzalez-Davidson, who was charged in absentia. The four face up to 15 years in prison if found guilty of both crimes.
The royal insult charges appeared to stem from a Zoom conversation among Gonzalez-Davidson and the Cambodian activists that he said authorities intercepted, though he denied anyone insulted King Norodom Sihamoni in the call.
"I've listened to that video a few times. Nobody is insulting anybody," he said.
Phil Robertson of Human Rights Watch said charging the activists with royal insult - also known as lese majeste - was inappropriate.
"Using the lese majeste charge against this group in Cambodia is a clear violation of freedom of expression. It's outrageous and unacceptable," Robertson said.
Mother Nature Cambodia was founded in 2013 by Gonzalez-Davidson and young Cambodian activists who began to film and post often-viral videos of environmental destruction that they blame on corrupt officials.
In May, a Cambodian court sentenced three other Mother Nature activists to between 18 and 20 months in prison after convicting them of incitement over attempts to organize a march to Hun Sen's residence to protest the filling-in of a city lake.
And in 2018, another court sentenced two Mother Nature activists to a year in jail after they were convicted of filming suspected illegal sand export activity.
Cambodia in recent years has also jailed dozens of political activists after the Supreme Court banned the most prominent opposition party in 2017.
Critics have called Cambodia a one-party state since elections in 2018 in which longtime Hun Sen’s party won all of the seats in parliament.