By Agence France-Presse
The impoverished Southeast Asian nation has long been a destination for sex tourists, with minors often the victims of a flesh trade aided by endemic corruption.
A CNN report broadcast on 25 July featured three girls who were reportedly rescued from the sex trade by Agape International Missions (AIM), a charity founded by an American pastor which has been operating in the country since 1988.
The girls had first appeared in a 2013 documentary by CNN on Svay Pak, a poor suburb on the outskirts of Phnom Penh, before the network decided to pay them another visit this year and follow up on their fate.
Until a crackdown in the early 2000s Svay Pak hosted a huge red light district notorious for child sex slaves and the documentary showed the trade still existed a decade on.
The head of the charity, American pastor Don Brewster, was quoted in last week's report as saying that Svay Pak was "at one point the epicentre" of the child sex trade.
He said things had dramatically improved in recent years but that some trade in minors still occured behind closed doors.
But Hun Sen, one of the world's longest serving leaders, took exception to the report.
"I cannot accept the insult by an NGO that was broadcasted on CNN... that said in Cambodia mothers sold daughters to be prostitutes," he told a graduation ceremony.
"This is an insult that cannot be tolerated. At any cost, this organisation must leave Cambodia. We cannot let them stay anymore," he added.
AIM did not respond to requests for comment.
Hun Sen and nationalists seized on an early version of CNN's online report which described the girls as Cambodian, when in fact they either spoke Vietnamese or Khmer with a thick Vietnamese accent.
CNN later removed the word Cambodian from their headline.
The network did not respond to an AFP request for comment but told the Cambodia Daily it "stood by its reporting".
Many of Svay Pak's poorest and most vulnerable inhabitants are indeed Vietnamese migrants.
But police raids, court cases and efforts by charities show ample evidence over the years that children from impoverished Cambodian families are also at risk of sex trafficking.
Hun Sen has long jousted with local and international NGOs, which he accuses of meddling in Cambodian affairs.
In 2015 he drove through a controversial and broadly-worded law that allows authorities to shutter any NGO that harms national security or the "traditions and culture" of Cambodia.