Usama bin Laden's alleged accountant boycotted a review hearing to evaluate his legal status, and his attorney was barred from attending the proceedings at the U.S. military prison in Guantanamo Bay (search), Cuba.

Ibrahim Ahmed Mahmoud al Qosi (search), 44, is one of four prisoners charged with war crimes at the U.S. naval base on Cuba's eastern tip. The United States says al Qosi, of Sudan, worked as Al Qaeda's chief accountant, paymaster and supply chief.

Defense attorneys have criticized the review hearings as a sham, warning their clients not to speak at any proceedings unless they have an attorney present. A decision on their status can still be rendered without the participation of the prisoners.

It was unclear whether al Qosi's boycott was connected to the barring of his attorney.

Although the government views the hearings as purely administrative, there is nothing that prohibits prosecutors from using testimony given at the review hearings during the military commissions, or trials. Al Qosi's trial is scheduled for December.

Air Force Lt. Col. Sharon Shaffer, al Qosi's defense attorney for the commissions, said she was not told when her client's review hearing was taking place and was barred from traveling to Guantanamo this week and last.

During the time that she has spent with al Qosi at the U.S. outpost, she and her Arabic translator have taught him how to ask — in English — for his attorney.

The review hearings are separate from the military commissions and are intended to determine whether each of the 549 prisoners at Guantanamo should be freed or were properly classified as enemy combatants, a classification that has fewer legal protections than a prisoner of war.

Al Qosi became the 30th detainee to boycott the so-called Combatant Status Review Tribunals (search), said a government official who spoke on condition of anonymity.

Defense attorneys and human rights groups say the tribunals don't satisfy a Supreme Court ruling allowing prisoners to challenge their detentions in civilian courts, where they would be allowed legal representation.

Shaffer said she planned to challenge al Qosi's classification as an enemy combatant during his commission or trial.

"We're really frustrated," Shaffer said. "Not to even be told when it was being held I think is really a travesty of justice because those cases are inextricably intertwined."

Australian prisoner David Hicks, 29, boycotted his review tribunal on Wednesday.

His attorneys also said they were not told when he would go before the tribunal and were barred from the U.S. outpost the week of his hearing. He has also been charged with war crimes.

Four other prisoners' cases went before the review tribunal Thursday, according to Navy Cmdr. Daryl Borgquist, a spokesman for the review tribunals.

Borgquist was not the official who confirmed the hearings for al Qosi or Hicks.

A 45-year-old prisoner, who attended his hearing Thursday, is accused of working for non-governmental organizations that the United States says helped fund the Al Qaeda (search) terror network. All of the detainees in Guantanamo are accused of links to Afghanistan's Taliban regime or to Al Qaeda.

Another detainee who attended his hearing was a 24-year-old accused of being recruited by Al Qaeda in 2001 and receiving training in Afghanistan. He allegedly participated in operations against U.S. or coalition troops. He was captured in Pakistan.

Also attending his hearing was a 20-year-old who has been held in Guantanamo for about two years. The U.S. government accused him of being a Taliban fighter who lived with his family in Kabul. He allegedly fought against the U.S.-backed Northern Alliance and was captured trying to flee to Pakistan.

A fourth detainee did not attend, but the U.S. government accused the 27-year-old of being an Al Qaeda fighter who traveled to Afghanistan in 1999 to attend a Libyan terror training camp near Kabul. He has been held at Guantanamo for more than two years.