PHNOM PENH - Cambodian Prime Minister Hun Sen on Sunday called for the closure of one of the country's main human rights groups because it was founded by detained opposition leader Kem Sokha.

A crackdown on critics of Hun Sen, the world's longest serving prime minister, has already led to the dissolution of the main opposition party and curbs on some independent media, prompting criticism from Western donors.

"The Cambodian Center for Human Rights (CCHR) must be shut down because it was created by foreigners not Cambodians. The ministry of the interior should look into this," Hun Sen told a group of garment workers.

Hun Sen described the opposition as "children" of the United States and said he told this to US President Donald Trump when they met in the Philippines earlier this month.

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The CCHR was founded by Kem Sokha in 2002 before he returned to a political career in 2007.

Kem Sokha was arrested in September and charged with treason for an alleged plot to take power with American help. His Cambodia National Rescue Party was dissolved on Nov. 16 by the Supreme Court, acting at the government's request.

Kem Sokha has rejected the charges against him, which the opposition calls a ploy to ensure Hun Sen extended over three decades in power in next year's election.

Western countries have condemned the crackdown. The United States has stopped funding for the election and the European Union has raised a potential threat to Cambodia's duty free access if it does not respect human rights.

Hun Sen has brushed off the criticism. Cambodia's biggest donor is now China, which has voiced support for measures to ensure stability.