The United States Tuesday condemned the Cambodian government for the arrest late last week of two leading human rights activists. The State Department said the action reflects an erosion of freedom in the Southeast Asian nation.

The United States has joined human rights groups in condemning the arrest of two Cambodian human rights activists, accused of defamation after criticizing Prime Minister Hun Sen.

The director of the Cambodian Center for Human Rights Kem Sokha, and Yeng Virak, head of the Community Education Center, were charged last Saturday over allegedly offensive material displayed at an event earlier in December marking international human rights day.

Cambodian officials were quoted as saying the charges were prompted by banners at the event branding Mr. Hun Sen a communist and traitor who had sold away Cambodian land in a border demarcation accord with Vietnam.

At a news briefing, State Department Spokesman Sean McCormack condemned the arrests as part of a worrisome trend in Cambodia and said U.S. concerns had been conveyed directly to Cambodian officials.

"This is the latest in a series of arrests and lawsuits targeting critics of the Cambodian government and the cumulative effect of which is to call into question the Cambodian government's commitment to democracy and human rights," he said. "Our Embassy immediately raised this issue with senior officials in the Cambodian government and we voiced our strong objections to these arrests and we urged the Cambodian government to reverse this - reverse the erosion of freedom and democracy.

The arrests have also drawn criticism from non-governmental organizations, including the International Republican Institute, which is affiliated with the U.S. Republican Party.

Institute president Lorne Craner, a former State Department human rights chief, said the arrests are a step backwards for democracy and human rights in Cambodia, and are inexcusable for a government that claims to be democratic.

Mr. Craner said it is time for Asian countries to show concern about the deteriorating human rights situation in Cambodia, and for the international community to make it clear to Mr. Hun Sen that such abuses cannot continue.

Two weeks ago, the State Department voiced concern over the 18-month prison term imposed in absentia on exiled Cambodian opposition leader Sam Rainsy, who had also been charged with defaming the prime minister.

Other critics of the government are in jail awaiting trial or have fled the country.

Mr. Hun Sen, a onetime commander in the communist Khmer Rouge guerrilla movement, rose to political prominence in the 1980s.

He has run the country with an increasingly authoritarian hand since his Cambodian Peoples Party won disputed elections in 1998.