A Cambodian refugee who returned to his country and became an MP and was then beaten by the Prime Minister's bodyguards says Australia should think twice about sending over refugees from Nauru.

Key points: Former refugee says Cambodia offers no sanctuary for refugees

Former refugee says Cambodia offers no sanctuary for refugees Australia gave Cambodia $40 million as part of a refugee resettlement deal

Australia gave Cambodia $40 million as part of a refugee resettlement deal HRW finds links between attacks, violence and senior officials

In October, Nhay Chamroeun and Kung Sophea were dragged from their cars and repeatedly kicked by a mob outside the National Assembly — both are MPs with the opposition Cambodian National Rescue Party.

Footage of the sustained assault showed dozens of bystanders, some with walkie talkies.

"It was so unexpected and cruel," Mr Chamroeun told the ABC.

"My wrist was broken ... all the front teeth broken, nose broken, and also eye socket's broken ... and also multiple chest injuries and ribs as well."

Three men handed themselves in to police claiming they initiated the attack because the MPs insulted them — a claim not supported by witnesses or the video footage of the incident.

Despite initial denials from authorities, all three confirmed in court they were members of the Prime Minister's bodyguard unit.

On Friday, they were sentenced to four years in prison for the attacks, with three years suspended.

Due to time spent in pre-trial detention they could walk free in five months.

"These three guys are going to take the fall," Phil Robertson, deputy director of Human Rights Watch's (HRW) Asia division, said.

"The real story is this was a coordinated attack ... it was quite clear that the bodyguard unit of the Prime Minister played a central role."

Cambodia offers no sanctuary for refugees: MP

A report released on Thursday by HRW detailed the links between those involved in the violence and top-ranking officials.

The HRW report explained that the organisation that organised the pro-government protest outside the National Assembly in October is run by the children of high-profile military and government figures.

At the time the group was known as the Youth Federation of the Legion of Cobras and its logo was almost identical to the bodyguard unit's insignia.

The three bodyguards sentenced for the attack are escorted by police. ( AFP: Tang Chhin Sothy )

"It's just a joke," said Mr Chamroeun after the verdict.

"The bodyguard unit should be held responsible ... the government should be held responsible."

Critics say the ongoing political unrest in Cambodia is just one reason Australia should not send refugees there.

Mr Chamroeun sought asylum in Thailand and then the United States but returned to Cambodia in 2013 to join the opposition party.

"I'm a former refugee ... [and] I appeal to the Australian Government to think twice about sending the refugees to Cambodia," he said.

Five refugees agreed to be resettled in Cambodia but four have since left.

"The whole idea that Australia had that somehow Cambodia would be a safe haven for refugees, I think was bonkers right from the beginning," Mr Robertson said.

Australia gave the Cambodian Government $40 million in aid as part of the refugee resettlement deal.

A further $15 million was pledged to the International Organisation for Migration (IOM) to provide support for the Nauru transferees and any other refugees in Cambodia at the time.

The IOM has confirmed that one refugee is still in Cambodia.