The US is allowing Sam Rainsy to use its territory to carry out terrorist activities against Cambodia, government spokesman Phay Siphan charged on Thursday.

Joining in the salvo, an academic said the US is also using Rainsy, the “acting president” of the Supreme Court-dissolved Cambodia National Rescue Party (CNRP), to further its geopolitical interests.

The claims came at a press conference held at the Council of Ministers on Thursday under the theme The Case of Insulting the King, just hours after new US ambassador Patrick Murphy arrived in Cambodia.

On Wednesday, the US State Department released a 45-minute video outlining its concerns regarding the political situation in Cambodia and urged the government to release former CNRP activists who were recently arrested.

“The US is concerned about the situation of political oppression by the Cambodian government against former CNRP activists, and we urge the Cambodian government to end political restrictions against every individual, including [CNRP president] Kem Sokha, and release political activists who have been aggressively and illegally arrested,” US State Department spokesperson Morgan Ortagus said in the video.

Siphan told Thursday’s press conference that it would be impossible for the government to do as requested by the US State Department.

“Concerning the request made to the Cambodian government, we cannot follow it. We have no power to interfere in the authority of the courts,” Siphan said.

He said the appeal came because the US had supported the CNRP.

“The statement of the US State Department official results from its emotions of having used the CNRP. If the US did not pay attention to it, it would seem like they had abandoned the group,” he said.

In accusing the US of allowing Rainsy to use its territory to carry out terrorist activities against Cambodia, Siphan said: “In the US, there is no law allowing the government to support terrorists or terrorism.

“So why do we say this is a terrorist group? First, it has organised a terrorist organisation on US territory – one that is not registered in the list of US organisations.

“Second, it has collected money in the US to be used in carrying out its illegal terrorist activities,” he said, referring to the CNRP.

On Rainsy’s tactics, Siphan said: “Sam Rainsy will take the blood of Cambodian people to use as his carpet on a march towards power. There will be no benefit besides the loss of life and a future of Cambodian people walking in darkness.”

Ros Chantraboth, a lecturer of Cambodian history, said at the conference that the US had used Rainsy to further its geopolitical interests without respect to national and international law.

“The group led by Sam Rainsy plays a role in US policy regarding Cambodia and the region. We see what Sam Rainsy announces or says every day especially his latest statement against the people of Cambodia and its monarchy.

“The US is Rainsy’s boss, and it allows him to make statements that chip away at the Cambodian Constitution. So the question is: Can we accept such activities?” Chantraboth asked.

If the US continued to support Rainsy’s terrorist activities, he said, it would fail to respect its own principles regarding terrorism.

He called on the US to stop supporting Rainsy’s actions, saying the CNRP co-founder was trying to destroy the Cambodian people, who were living in peace and security and enjoying economic growth.

Ministry of Justice spokesman Chin Malin said at the conference that Rainsy was using all possible means to further his interests and take power for his group, even going so far as to insult his people and nation and tarnish the honour of the King.

“He offers to bow his head to foreigners to ask them to impose sanctions on the Cambodian people for his political interests,” Malin said.

However, Ou Chanrath, a former CNRP lawmaker, said there was no evidence proving the US was supporting Rainsy in carrying out terrorist activities against Cambodia.

He said the US was only trying to make the Cambodian government show greater respect for democracy and human rights.

“The US is not using Sam Rainsy to further its interests. The US wants Cambodia to grow and see its politics back on the right track. This accusation [by government officials] may even affect relations between Cambodia and the US, which will bring no benefit,” Chanrath said.

Kin Phea, the director of the International Relations Institute at the Royal Academy of Cambodia, also said the accusations could affect Cambodia-US relations, which already were not at its best.

US embassy spokesperson Emily Zeeberg declined to comment when contacted.