- Police raided the home of Opposition Leader Kem Sokha
- MP Mu Sochu says "a red line has been crossed" and "there is almost no hope for democracy"
- Mu Sochua is urging Australia to convene a special meeting to discuss the country's political direction
On Saturday night, police raided the home of Kem Sokha, head of the Cambodian National Rescue Party (CNRP), and sent him to a remote prison near the Vietnam border.
"The red line has been crossed," opposition member Mu Sochua said.
"There is almost no hope for democracy unless the international community — including Australia — takes a very firm stand to the Government of Cambodia," she told the ABC.
Mu Sochua said Australia has a special role in Cambodia, as one of the signatories of the 1991 Paris Peace Accord and a leader within the United Nations peacekeeping mission that gave birth to Cambodia's flawed democracy.
But critics say a $55 million deal to resettle refugees in Cambodia has largely silenced Australia's voice on democracy and human rights.
"We have not seen anything coming from the Australian Government yet [in this case] … and we urge that there be not just a statement, but Australia to take a very strong stance, with other democratic nations," Mu Sochua said.
Specifically, she wants Australia to join other signatories of the Paris Peace Accords to convene a special meeting and discuss the country's political direction.
So far, Australia's response has been far milder.
"The Australian Government is concerned by the arrest of Cambodian opposition leader Kem Sokha overnight," a spokesman from the Department of Foreign Affairs and Trade said.
"We urge Cambodian authorities to handle the matter in an open and transparent manner, and to take all necessary steps to maintain an open democratic space in which all voices can be heard."
Kem Sokha's daughter also urged Australia to do more.
"Australia has a big role to play here … given that many ruling party people use it as their base outside of Cambodia," Monovithya Kem said.
"A dictatorship in Cambodia ultimately weakens Australia's position and security in the region."
'This regime refuses the possibility of defeat'
Kem Sokha has long been in the sights of the ruling Cambodian People's Party.
Last year he spent months living inside his office to avoid charges relating to a prostitution case that many believed was politically motivated.
This time he has reportedly been charged with treason, after pro-government media last week accused him of being part of a conspiracy with America to overthrow the Government.
No evidence has been provided and the charge is again widely thought to be politically-motivated.
"I am not surprised by the latest crackdowns including the illegal and barbaric arrest of my father," said his daughter, Monovithya Kem, who is also deputy director the CNRP's Public Affairs department.
"This regime refuses the possibility of defeat via free, fair elections."
The arrest is part of a wider crackdown on critics that has shut down influential newspaper The Cambodia Daily, banned 19 radio stations from broadcasting independent content and kicked out the non-partisan pro-democracy organisation, the National Democratic Institute.
The offensive comes ahead of an all-important national election next year.
Prime Minister Hun Sen has ruled for 32 years but now faces a grave political threat from the opposition, as many Cambodian's vote against the corruption and nepotism of the past decades.
From grenades to lawyers
Hun Sen has made it clear he will not go gently.
"To ensure peace and to continue the development, the only option is that the [Cambodian People's Party] must win elections at all stages," Hun Sen said, before local elections in June.
"To ensure the lives of millions of people, we are willing to eliminate 100 or 200 people because we have seen bitter past experience," said the Prime Minister, who defected from the Khmer Rouge and was placed into power by the Vietnamese.
It is no empty threat.
In 1997 grenades were thrown into an opposition rally and last year two opposition MPs were brutally assaulted by the Prime Minister's bodyguards right outside the National Assembly.
But lately, the ruling party's weapon of choice has been Cambodia's notoriously pliable courts.
Former opposition leader Sam Rainsy now lives in exile after several convictions, again widely thought to be politically motivated.
But unlike Sam Rainsy, the opposition's current leader Kem Sokha has stayed in Cambodia to face Hun Sen's threats.
"I am very proud of what my father has done in Cambodia for over 20 years, planting the seeds of change in the grassroots from his years as a human rights leader to a politician," Monovithya Kem said.