CANBERRA, Australia (AP) – The government would be powerless to reduce any sentence served in an Australian prison by a Guantanamo Bay detainee who this week admitted to aiding Al Qaeda, the attorney general said Thursday.

Former kangaroo skinner David Hicks, 31, is likely to be transferred to a prison in his hometown of Adelaide soon after he is sentenced by an American military commission at the American naval base on Cuba this week.

Hicks, who was sent to Guantanamo weeks after his capture by the American-backed Northern Alliance in Afghanistan in December 2001, pleaded guilty this week to a war-crime charge of providing material support to terrorism.

Attorney General Philip Ruddock said an agreement between Washington and Canberra formally came into effect Thursday that would allow Hicks to apply to return to Australia if he were sentenced to prison.

“The arrangement provides for enforcement of the nature and duration of any sentence, so that the Australian government could not unilaterally shorten or dispose of any such sentence,” Mr. Ruddock told Parliament.

But Hicks’ father said his son could use the Australian courts to contest the legality of whatever sentence, if any, is imposed. Australian legal groups have condemned the American military commission system as unfair.