Australia must hold a royal commission into the behaviour of the immigration department and its policy of offshore processing. I can’t predict an outcome, but if I had my way I would dismantle the department and totally rebuild it.

I’ve known of the situation on Manus Island for some time, and learned that it was worse than impossible for families of refugees. The accommodation is absolutely deplorable – rotting tents and camps, overcrowding. This isn’t an offshore processing centre. It’s an offshore prison.

I’m sure the Australian people would rebel against that sort of situation if they were fully aware of it, but they aren’t – because any attempt for the media to get in and have a look has so far been denied.

The immigration department have known what's been happening on Manus Island, they have known what’s been happening on Nauru, and if they had for one moment thought that these centres were being run in way they would have allowed the media in to report on it, to photograph it and to speak with people. But none of that has happened, and now we learn of claims of detainees suffering sexual abuse which is being investigated.

I would hazard that many of the people in the immigration department should not be working there. I’ve got no doubt there are good people also, but a department that is happy enough to run Manus Island and Nauru the way they have has something grievously wrong with its culture – which is why there needs to be a royal commission to allow Australians to understand what has been done in their name.

This isn't the first time the department have acted in disgraceful ways. There were two earlier inquiries into their misdeeds. Both reports were severe in their criticism of a department which had unlawfully imprisoned an Australian, Cornelia Rau, for many months, and which had deported Vivian Solon, also Australian, to the Philippines.

Tony Abbott and Scott Morrison announce the Coalition's asylum seekers policy, 'Operation Sovereign Borders'. Photograph: Dan Peled/AAP Photograph: DAN PELED/AAPIMAGE

The case for a royal commission is overwhelming, but there are already difficulties. The government has now – I believe as a result of this week's coverage – virtually already removed people from Manus Island. Depending on where they’ve gone, that would make it very difficult for an inquiry to completely piece together what has actually happened.

Where have those people been sent? Will there be a proper inquiry into what was going on? If there was abuse, who was abused? Who were the abusers? And who allowed it to happen, and how did these conditions prevail?

Whatever policies Australia adopts in relation to asylum seekers, we should not be running camps which are reminiscent of Soviet gulags.

The policies of both the government and the opposition are designed to be extraordinarily harsh on the most vulnerable. But if people really are fleeing terror or believe that they are under threat in their own lands, then the policy of deterrence is never going to work because we can’t match their fear of being brutalised, killed, or jailed without trial.

For the Coalition, with its Operation Sovereign Borders policy, to now relate the asylum seeker problem back to Australian sovereignty and border protection (as though asylum seekers were ever a threat to Australia’s integrity as a sovereign nation), is nonsense. It is part of an approach designed to suggest to Australians that their way of life is under threat, making it easier to pursue harsh policies which Australians might otherwise reject.

Perhaps in spite of all the publicity that comes from the government and opposition competing to see who can be the nastiest, underneath it all those seeking safety here still believe that Australia is a reasonable nation. And I hope we still are, at the end of the day.