Liz Thompson, a former migration agent turned whistleblower, has described the administration of the Manus Island detention centre as 'ridiculous' and claims she was instructed to tell detainees their only option was resettlement in Papua New Guinea.



“They (detainees) watch the news, they read the newspapers, they watch what’s going around in the camp, they know there’s no decision from the Papua New Guinean Government on resettlement," she told Dateline's Mark Davis.



"So what that means is… you’re never getting out of this camp, it’s indefinite detention."



A spokeswoman for the Minister for Immigration and Border Protection, Scott Morrison, denied that Manus Island detainees had been told they would not be resettled in PNG.



“With regard to reports that the transferees were advised that they will not be settled in PNG, the Minister has been advised that those reports are false," she said in a statement.



Ms Thompson's allegations come as the Immigration Department faced questions on the recent riots on Manus Island from a Senate Committee.



The department head described detainees pushing down fences and throwing rocks before police discharged a gas canister and fired warning shots.



Immigration and border protection secretary Martin Bowles said work was needed to uncover what happened.



"There are a range of other reports, there are interviews that need to happen with the independent reviewer to start to work through the myriad of information that's out there," he said.



'Fake' processing system



Ms Thompson is the first staff member to publicly resign from Manus Island following a recent outbreak of violence which left one dead.



She was originally bought in to conduct refugee-assessment interviews and claims she was told to tell inmates their only option was resettlement in Papua New Guinea.



Ms Thompson said she knew their only option was indefinite detention, and so did they.



"I would not go back because there is no process, nothing for me to do, no process to assist people with - it's fake," she said.



"It's not designed as a processing facility, it's designed as an experiment in the active creation of horror to deter people from trying in the first place."



Ms Thompson told Dateline she was given a script to follow while conducting refugee assessments.



"We were informed that we were not to discuss resettlement, we were not to discuss third country options," she said.



"It was made very clear to us every day, sometimes even twice a day, under the threat of being removed from the island, we were not to talk about a third country, we were not to suggest there were any resettlement options, we were not to suggest they would be able to get off PNG," she said.



“We knew that this was ridiculous, but we were lying to people and we were told to keep that message going to keep it clear."



"What's not happening is any clarification on where they are going to end up."



“There is no process, the process doesn’t lead anywhere except indefinite detention."



Ms Thompson believes this is partly behind the violence that rocked the Manus Island detention centre last week.



She was in the compound on Sunday night and says she could hear the noise from her room.



"What they wanted was not just the interviews, the process, something to feel better about, something to feel involved in. They want to know where they are going," she said.



"I believe what happened was completely predictable, that tensions were allowed to build up, that misinformation was allowed to circulate, that people were allowed to be driven into a frenzy about what was going to happen."



“That’s what Manus Island is, it’s the active creation of horror in order to secure deterrence. And that’s why I say again, Reza Barati's death is not some kind of crisis for the department, it’s an opportunity to extend that logic, one step further – to say ‘This happens, but deterrence continues, Operation Sovereign Borders continues.”