Mr Dutton said the visit of Sok Phal, a three star general and head of Cambodia's immigration department "reaffirmed the close working relationship between Australia and Cambodia on a variety of immigration issues". General Sok Phal was a director of one of a number of secret death squads called A-Teams that infiltrated and subverted groups opposing the country's now ruling Cambodian People's Party in the early 1990s, according to a 2012 report by Human Rights Watch, which relied on United Nations reports. Australian Immigration Minister Peter Dutton and Cambodian Department of Immigration director-general Sok Phal shake hands in Phnom Penh last month. The United Nations issued a report in 1993 listing dozens of killings, enforced disappearances and torture by groups linked to the party during a UN mission to bring peace to the country after decades of civil war and foreign occupation. Human Rights Watch said General Sok Phal has benefited from a culture of impunity for Cambodia's military elite under strongman prime minister Hun Sen, rising through the ranks to become one of the regime's most powerful officials. General Sok Phal has been deeply involved in Australia's controversial $55 million agreement to send refugees to impoverished Cambodia from the tiny Pacific island of Nauru.

Mr Dutton presented him with an Akubra hat during a visit he made to Phnom Penh in September to salvage the agreement, after Cambodia said it had no plans to take any more than the four refugees who arrived in June. Peter Dutton (left) and Sok Phal (right) meet in Phnom Penh last month. The Australian government has moved closer to Cambodia since former immigration minister Scott Morrison signed the agreement at a champagne ceremony last year, including inviting Mr Hun Sen to make an official visit to Australia early next year. Australia gave Cambodia $40 million for signing the agreement and has spent another $15 million getting only four refugees to the country. The US and other Western nations and human rights group have been highly critical of Mr Hun Sen for presiding over 30 years of corruption, brutality and a readiness to subvert popular will in Cambodia.

The deal with Australia was a long-awaited diplomatic triumph for Mr Hun Sen, who in the early 1970s was an officer in the murderous Khmer Rouge before he defected to Vietnam. Mr Dutton refused to say whether he knew of General Sok Phal's past. General Sok Phal could not be reached for comment but in 2012 Cambodia's government criticised the Human Rights Watch report that named him and other party officials, saying it was baseless and politically motivated. The Myanmar refugee's decision to return home has been expected. "He saw other people fleeing Myanmar, so he followed and ended up in Nauru," said Ministry of Interior spokesman Khieu Sopheak. "He was remorseful when he couldn't settle in Australia," he said. Cambodian officials say two more Rohingya Muslims on Nauru have agreed to give their hope of living in Australia to travel to Cambodia, where they will receive thousands of dollars in cash, accommodation, training and other benefits for 12 months. But after that they will need to fend for themselves in one of Asia's poorest nations. Mr Dutton indicated the three other refugees who arrived in Phnom Penh in June had moved from a luxury villa paid for by Australia to their own accommodation.