Prime Minister Hun Sen on Sunday appeared to suggest he would have assassinated opposition leaders Sam Rainsy and Kem Sokha had he known they were promising to “organise a new government” in the aftermath of the disputed 2013 national elections.

In a clip from his speech to garment manufacturers, released on Tuesday night, Hun Sen can be heard referencing a 2013 video of Rainsy and Sokha calling for supporters to “prepare” for the opposition Cambodia National Rescue Party to “organise a new government”, and referring to December 29, 2013, the date of a mass nonviolent protest, as the “final day”.

In his remarks, however, Hun Sen suggested the call to action was a capital offence.

“If I had seen that at the time, they would already be dead; it would be their funeral,” Hun Sen says in his speech. “They are lucky that I missed it. If I had watched that clip on the day they announced that, a few hours later, I would have attacked them from all sides at once.”

A huge nonviolent march took place in Phnom Penh on December 29, 2013, to contest the results of that year’s elections, which saw the opposition make staggering gains. The government has since sought to characterise the opposition protests – and simultaneous wage strikes in the garment industry – as a so-called “colour revolution” to topple the government.

The allegations precipitated the widely condemned dissolution of the CNRP last week, and the jailing of Sokha, its president, on charges of “treason”.

It was not clear whether the premier’s remarks referred to protesters or CNRP leaders, though government spokesman Phay Siphan said he was referring to Rainsy and Sokha.

“It’s not a threat,” Siphan said. “If someone tries to topple the government – the legal or legitimate government – the government has a right to protect themselves.”

When asked whether that included the right to kill people, Siphan said the state was empowered to “do anything to protect the government”.

“Would you like to try it? Try to kill the prime minister, or try to kill the president? What would happen to you?” Siphan asked. “It’s not a joke, national security.”

Hun Sen echoed this sentiment in the run-up to the June commune elections, threatening to “eliminate 100 or 200 people” to ensure the stability of Cambodia in the event of protests against the result.

But Rainsy, who is in self-imposed exile, challenged that narrative yesterday, saying he and Sokha “did not call for anything violent to topple the government”.

Indeed, opposition protests at the time, which took place over a span of months, were studiously nonviolent, and often featured calls for Hun Sen to step down in light of electoral irregularities.

“We wanted to demonstrate our strength, a show of our unity,” Rainsy said.

The premier’s comments were roundly condemned by human rights advocates and political analysts yesterday.

“As the prime minister of the country, he should not talk about killing like this,” said political analyst Lao Mong Hay, adding the “speech shows he was ready to go to war against citizens”.

“This is condemned,” he added. “You have arms. They don’t have arms. And they are your citizens. There was no decision [by a court] to punish them.”

Phil Robertson, deputy director of Human Rights Watch’s Asia division, said in an email that the comments showed “the real Hun Sen”.

“Diplomats and UN staff who thought that compromise would bring Hun Sen around should remember this swagger of a dictator unbound who knows he has the judiciary is in his pocket and the military backing him all the way,” Robertson said.

British human rights lawyer Richard Rogers, who filed a complaint asking the International Criminal Court (ICC) to investigate the Cambodian ruling elite for widespread human rights violations in 2014, said he would file the clip as new evidence of the government’s willingness to persecute political dissidents.

“It shows that he is willing to order the murder of his own people if they challenge his rule,” Rogers said. “These are not the words of a modern leader who claims to lead a democracy.”

The ICC has not yet started an investigation on the complaint, and observers have suggested the case faces an uphill battle.

Human rights lawyer Billy Chia-Lung Tai said Hun Sen’s comments are “incredibly concerning” regardless.

“It certainly contributes to this notion that he has no respect for human rights ideals,” Tai said. “That he would, in a way, contravene his own constitution to kill people exercising their constitutional right to demonstrate.”

“The Human Rights Office [OHCHR] should be concerned and should speak up about it,” Tai added.

Siphan, who said he had not seen the original video clip, said Rainsy and Sokha’s actions nevertheless amounted to staging a coup.

When asked whether the government made a distinction between people voting for a new government and toppling the government, he replied, “I don’t need to explain to you. You have to find out and have to research by yourself.”