The calls from Australia come as the United States said Cambodia should "undo its recent actions" against the country's main opposition, after the Supreme Court dissolved the party and banned more than 100 politicians.
The decision means Prime Minister Hun Sen could continue his leadership unopposed for the foreseeable future.
Lawyer Sawathey Ek from the Cambodian Australian Federation told SBS News that the move did not come as a surprise to most Cambodians given the “mistreatment” over the last 20 years, but he felt many were taken aback by the lack of regard for the international community.
He claimed the South-East Asian nation has “absolutely” killed off democracy and said it was a step back from the Paris Peace Agreement in 1991.
“[That] agreement was supposed to guarantee Cambodia’s participation in this democratic process but this is obviously a killing process for that investment,” he said.
“At this stage, what we are talking about is a country that is being run by one person, and that is Hun Sen alone. I don’t think that anybody can do anything except the international community. We have to come back to Australia, and Australia being the core signatory to the Paris peace accord.”
“We would ask the Australian government to reopen that and force Hun Sen to come to the agreement that he was put in charge of that country following the Paris peace agreement. That was supposed to guarantee Cambodia long-lasting peace and that is now being killed off,” he added.

Cambodia's Prime Minister Hun Sen. Source: AAP
“I don’t think he’s done this because he’s going to lose next year’s election as such. I think it’s always been the plan. I think you’re actually talking [about] a dictator who always had the plan to be in power for the rest of his life.”
He said he wanted to call on the Australian government on behalf of his community to “speak up or sanction” Hun Sen.
“For somebody to be called a prime minister, and banning the entire 110 MPs and activists without trying, is completely a joke. You are promoting an administration that Australia invested so much in. Australia is silent. Malcolm Turnbull is accepting this. We demand that the Australian government make Hun Sen accountable because the only [thing] he will be concerned about is the international community.”
Foreign Minister Julie Bishop said the development has serious implications for democracy in Cambodia.
"As a friend of Cambodia, Australia urges the Cambodian government to allow all its citizens to exercise their democratic rights, particularly ahead of the 2018 national election," she said in a statement.
Ms Bishop cited a series of troubling actions, including reduced access to free media, restrictions on civil society and intimidation of the opposition.
Earlier, the White House pleaded: “We call on the Royal Government of Cambodia to undo its recent actions against the CNRP (Cambodia National Rescue Party). On current course, next year’s election will not be legitimate, free, or fair."