The Immigration Minister Scott Morrison has defended his government's controversial boat turn-back policy after it was heavily criticised by the United Nations, saying that he was "not surprised" by the international body's opposition.

Representatives from the United Nations publicly voiced their opposition to the turn back policy saying Australia was breaching refugee convention by turning back asylum seekers to Indonesia. Instead, they are calling on Australia to process asylum seekers who reach Australian waters.

"I completely disagree," Scott Morrison told Sky News on Wednesday morning. "I'm not surprised, they have always opposed our turn-back policy.

"But I'll tell what Australia's national shame was when it comes to this issue, almost 1200 people dead," he said. "That's national shame. That's the regional shame."

The strong critique from the UNHCR came after a two-day conference in Jakarta, attended by Australia’s deputy ambassador to Indonesia David Engel and representatives of 14 other countries, to discuss the protection of refugees in the region.

Opposition immigration spokesman Richard Marles said unilateralism was not meant to be a "long term sustainable answer in the flow of people coming by boat to Australia".

"We are worried about what this means in the context of our relationship with Indonesia in circumstances where they do not agree with this policy," Mr Marles said.

The rebuke from the UN has followed the publication of explosive footage by Fairfax Media showing Manus Island security guards attacking asylum seekers 24 hours before Iranian Reza Barati was killed.

Mr Morrison said the footage should be turned over to the independent investigation led by retired public servant chief Robert Cornall.

"I would say to anyone who has information of that nature: that's the place for it to be investigated," Mr Morrison said. "I want to get to the bottom of this. I want to make sure I know exactly what has happened."

with Michael Bachelard

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