Foreign affairs spokesman for the opposition Labour Party, Kevin Rudd, said Prime Minister John Howard needed to start discussing repatriation of its citizens with the United States immediately.
"John Howard, on this question, needs to show some guts," Rudd told reporters.
David Hicks and Mamduh Habib have both been held under appalling conditions in Cuba without legal representation or support from their governments since 2001.
Hicks' family also believes the government is not doing enough to guarantee the former Taliban volunteer is charged with specific offences and not sentenced to death.
Both detainees face the prospect of military trials that can pass death sentences, although Australia has long opposed capital punishment.
Hicks' lawyer, Stephen Kenny, has also urged the government to pressure the United States to release him for trial at home instead of before a US military court, where he would only have access to army lawyers.
"John Howard ... needs to show some guts"
Opposition Labour Party
But the government says it will only consider repatriating its citizens held in the infamous Cuba camps if they are found to have broken the law, according to a government spokeswoman on Tuesday.
The two would be brought back from Camp X-ray if they can be charged in Australia, said Attorney General Daryl Williams’ representative. If they can not be charged, no representations will be made on their behalf.
Many Australian legal experts believe the captives would be released should they return home as they had infringed no laws by joining the Taliban in Afghanistan.
Camp X-Ray detentions breach
international laws and conventions
To date, the government has only said it made clear to the United States it does not support the death penalty, but it does not appear to have sought clear assurances that Hicks or Habib would not be executed.
The United States launched strikes on Afghanistan to flush out members of al Qaeda, killing over 4,800 Afghani civilians in the process and arresting hundreds.
Held in camps inside Afghanistan and Cuba in conditions condemned by all international human rights organisations, the age range of detainees is from 13 to the mid-80s in some cases.
Six hundred and eighty men are currently held at Guantanamo, in conditions that violate international human rights conventions.