An Australian, who is the first prisoner to face a new U.S. war crimes tribunal in Guantanamo Bay, unexpectedly pleaded guilty on Monday to a charge of supporting terrorism in Afghanistan.

David Hicks, 31, was the first of hundreds of Guantanamo detainees to make such a plea at the U.S. Navy base since the first terror suspects were taken there in 2002.

On Monday, he also became the first detainee to face prosecution under revised military tribunals set up after the U.S. Supreme Court struck down the Pentagon's previous system last year.

A panel of military officers will now determine Hicks sentence, likely by the end of the week.

It was not immediately clear if there was a former plea bargain.

But U.S. Air Force Col. Morris Davis, chief prosecutor for the tribunals, denied there had been a plea deal.

"I wouldn't describe it as that, I would describe that the accused has elected to enter a plea of guilty to a specification of a charge," Davis said.

Hicks' military attorney, Marine Corps Maj. Michael Mori, told the judge, that his client was pleading guilty to one of two counts of providing material support for terrorism and not guilty to the other.

Asked by the judge, Marine Col. Ralph Kohlmann, if this was correct, Hicks said somberly: "Yes, sir."

According to the charge sheet, Hicks spent weeks trying to join the fight in Afghanistan alongside the Taliban against invading U.S. forces and their Northern Alliance allies.

The count he pleaded guilty to says he intentionally supported a terror group hostile to the United States.

But Hicks denied the charge that he supported preparation, or carrying out, an act of terrorism.

The charge carries a maximum penalty of life in prison, but Davis has said he would seek a sentence of about 20 years.

The five years Hicks has already spent at Guantanamo will be considered a mitigating factor in determining his sentence.

Return to Australia

Davis told reporters Hicks will likely be home by the end of the year.

In the days leading up to the hearing, defence attorneys had painted Hicks, a former kangaroo skinner, as severely depressed.

They said he was considering a plea deal to end his five-year imprisonment at the U.S. naval base in Cuba.

The United States has agreed to let Hicks serve any sentence in Australia.

"This is the first step toward David returning to Australia," said David McLeod, an Australian attorney for Hicks.

Hicks entered the plea only hours after an emotional reunion with his sister and father, Terry Hicks, whom he had not seen since August 2004.

In Australia, Foreign Minister Alexander Downer said he expected Hicks would return home, where his case has become a major political issue.

Mounting criticism over his continued detention has cost Prime Minister John Howard support ahead of elections due this year.

"I am pleased for everybody's sake that this saga ... has come to a conclusion," Downer told Australian Broadcasting Corp. radio.

But he added: "My view was always that the legal process had just taken far too long."

Criticism of tribunals

Defence lawyers and human rights groups say the new military tribunal system, approved by the U.S. Congress last year, is also flawed because it does not offer the same protections as U.S. courts.

"In a narrow sense, David Hicks was not legally coerced today to issue a plea, but he was operating in the background of a highly coercive system that has held him for five years and did little today to restore his faith ... in the legitimacy of the system," said Jennifer Daskal of Human Rights Watch.

A challenge of the reconstituted tribunal system is pending before the nation's top court. Lawyers for detainees have asked the high court to step in again and guarantee that the prisoners can challenge their confinement in U.S. courts.

Lawyers for detainees have asked the high court to step in again and guarantee that the prisoners can challenge their confinement in U.S. courts.

There are about 385 prisoners held by the United States at Guantanamo.

Among the detainees is Khalid Sheikh Mohammed, an al Qaeda member who earlier this month confessed to planning the Sept. 11 attacks and other terror acts.

That military panel determined he was an enemy combatant who could later face charges.

But Hicks, unlike Mohammed, has been painted by the U.S. military as a minor figure.

With files from The Associated Press