Following the riots at Villawood Detention Centre last week, 22 asylum seekers from Iran and Afghanistan were transferred to the maximum security gaol at Silverwater. They are still to be charged.

The Immigration Department believes their imprisonment is lawful under the terms of the Migration Act, which is disputed by Australian Lawyers Alliance director Greg Barns.

"It is extraordinary for a person to be deprived of their liberty and to be removed from their place of residence into custody when they haven't been charged and still haven't been charged four to five days later," Barns told Lawyers Weekly. "I think the Immigration Department potentially acted illegally in what they did."

In particular, Barns believes that the imprisonment of the asylum seekers violates state and international laws.

"Holding people in solitary confinement when there is no justifiable basis for doing so is a breach of the relevant corrections legislation in New South Wales," Barns said. "It is certainly in breach of Australia's international obligations. In particular, the convention on torture and other forms of cruel and unusual punishment."

Australia was one of the first countries to sign the United Nations Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment in 1985.

Barns doesn't believe domestic laws such as the Migration Act trump Australia's international obligations.

"The High Court has said on a number of occasions that when there is any ambiguity, domestic laws must be read in such a way as to ensure that Australia's international obligations are met."

The secretary of the NSW Council of Civil Liberties, Stephen Blanks, is acting for the 22 asylum seekers. He confirmed with Lawyers Weekly that the vast majority of his clients have spent the whole of their detention at Silverwater in solitary confinement, and are handcuffed when he meets with them.

He believes their continued detention without charge at Silverwater violates the principles which underpin Australia's legal system.

"The fact that there is a technical ability under the Migration Act to treat state prisons as immigration detention centres doesn't make the treatment of these asylum seekers correct," Blanks said. "If you asked a first year law student if you could end up in a maximum security prison in solitary confinement without being convicted or charged with any offence, you would get a pretty high response of no."

Blanks has filed official complaints to the Human Rights Commission and the NSW Ombudsman about the treatment of his clients.

When asked by a journalist yesterday if people held in maximum security gaols should be charged with something, Attorney-General Robert McClelland said that "is usually the case", but he is "not aware of the specifics in those circumstances [Villawood riots]."

Up to 100 detainees at Villawood were involved in the riots last week that destroyed nine buildings.