Some of the detainees released from immigration detention were sent into the community without visas, a revelation that appears to contradict what the federal government has said in recent days.

Key points:

The government has released 83 people from immigration detention following a High Court ruling

Government ministers have repeatedly said people were released on bridging visas

The ABC has been told at least a dozen people were released without visas

A letter provided to some of the detainees upon release, which the ABC has seen, stated their status "at least for now" was "as an unlawful non-citizen".

The ABC has been told at least a dozen people left immigration detention at the weekend as unlawful non-citizens and had their bridging visas confirmed across Monday and Tuesday.

But on Sunday, Foreign Minister Penny Wong said former detainees had been placed on bridging visas, which would allow federal authorities to monitor their movements and keep the community safe.

"As people are being released, visa conditions are being applied to bridging visas for those people and we will continue to work through the judgment when it is handed down and the implications of the decision, but I make the point, people are being released with conditions, and we will ensure that law enforcement authorities, federal and state, work together."

On Monday, Immigration Minister Andrew Giles insisted federal authorities had oversight of the cohort because they were on visas.

"All of whom are on appropriate visa conditions," he told RN Breakfast.

The government has been forced to release 83 people from immigration detention, following a landmark High Court ruling last week.

That ruling found that it was unlawful for the government to indefinitely detain people in immigration detention, affecting 92 people who were in detention. With 83 now released, the status of a further 11 people affected by the ruling remains unclear.

Mr Giles on Tuesday told parliament three murderers and "several" sex offenders were among the cohort released into the public.

Senior government ministers repeatedly indicated all were on bridging visas, which meant they could have conditions attached to their employment and movement, but a letter from the Department of Home Affairs suggests otherwise.

The Department of Home Affairs letter handed to some people explained they could be issued with a visa at a later date, but no guarantee was provided.

"The Minister for Immigration, Citizenship and Multicultural Affairs will consider regularising your status by way of the grant of a Bridging (Removal Pending) (subclass 070) visa which, if granted, will enable you to reside lawfully in the community."

A person who does not have a visa is not able to open a bank account or apply for a job.

The government on Tuesday said 81 people are on bridging visas but the ABC has asked how many were initially released as unlawful non-citizens.

Ensuring community safety

The government has repeatedly stated community safety would be ensured by placing visa conditions on former detainees, which would allow federal authorities to monitor them.

Refugee Legal executive director David Manne said he was surprised that some people had been released as unlawful non-citizens.

"It is critical people be released with an appropriate visa on release and not be left without a visa in accordance with the law," he said.

"Under the Migration Act, it is very clear you either don't have a visa and must be detained, or if you do have a visa you must not be detained so in accordance with the law people should be released on an appropriate visa."

He also explained that releasing people as unlawful non-citizens left them in a "precarious situation".

"Without a visa someone can't work, they can't access appropriate medical care," he said.

The Home Affairs Department has confirmed financial, accommodation and medical support has been offered to all former detainees.

While Mr Giles insisted the cohort would have conditions imposed on them attached to their visas.

"And that's obviously one of the bases upon which we assure community safety," he told RN on Monday.

"Those visa conditions include regular reporting."

The ABC has asked Mr Giles and Home Affairs Minister Clare O'Neil's offices about what happens if people breach their visas. That request was referred to the Department of Home Affairs and Border Force but neither are yet to respond.