Cambodian Prime Minister Hun Sen has threatened to "beat" protesters if they burn his image at a summit of South-East Asian leaders in Sydney next month.

Hundreds of Cambodians living in Australia are expected to rally against Hun Sen when he attends the ASEAN-Australia Summit on March 17-18.

"I want to remind those who plan to demonstrate against me that my visit is an honour for their government," Hun Sen said in a speech, according to translated subtitles.

"If they burn my effigy … I will pursue them to their houses and beat them up.

But instead of backing down, protesters are saying thanks for the idea.

"We didn't plan to burn Hun Sen's effigy, but he is the one who reminded us yesterday," Cambodian-Australian Melbourne resident Va Malina told the Phnom Penh Post.

Hong Lim, the member for the Victorian state seat of Clarinda and who was born in Cambodia, told the Post that Australians were entitled to peacefully protest.

"The whole irony is that this event he's coming to attend is about Australia and ASEAN jointly fighting against terrorism … and the terrorist Hun Sen is threatening to bring terrorism into Australia," Mr Lim said.

'No Hun Sen, no ASEAN'

Hun Sen also warned he would boycott the ASEAN-Australia Summit or veto any joint statements if there was pressure from the member states, according to the Phnom Penh Post.Hun Sen was referring to an apparently leaked private phone call between members of the now-banned main opposition party, Cambodia National Rescue Party (CNRP), who said the Cambodian Government would face pressure from the United Nations, Australia and ASEAN countries.

"If there is no Hun Sen, there will be no ASEAN," the Phnom Penh Post quoted him as saying in a speech to Cambodian garment workers.

"I'll just give the reason that in 2018 I cannot go abroad because I am busy with the election" scheduled on July 29.

"This means Australia won't be able to hold the meeting. If there is no consensus it is impossible."

Opposition leader Kem Sokha has been in jail since September. ( Reuters: Samrang Pring )

Cambodia's democratic aspirations have been dealt a crushing blow last year, with the country's Supreme Court dissolving the main opposition CNRP last year and jailing of its leader Kem Sokha, who had been charged with treason.

Chief Judge Dith Munty, who is a senior ruling party member, announced the nine-member court's unanimous ruling last November.

He said 118 opposition party members would also be banned from politics for the next five years, and the verdict could not be appealed.

Meanwhile, Australian filmmaker James Ricketson, accused of espionage in Cambodia, has been in pre-trial detention since his arrest in June, 2017, prompting Foreign Minister Julie Bishop to the Cambodian Government to express concern about the case.

Mr Ricketson is facing spy charges after flying a drone over a political protest in the capital Phnom Penh last June.

If convicted, he could be jailed for 10 years but he denies the charges.

Last week, former opposition leader Sam Rainsy said Mr Ricketson was a scapegoat and his arrest was designed to frighten and deter foreign journalists from writing critical reports of Hun Sen's Government.

ABC/AAP