A court sketch done in May shows Guantanamo detainee Ali Hamza al-Bahlul, far left, holding up a handwritten sign calling for a boycott of his trial. (Janet Hamlin/Associated Press)

A jury of U.S. military officers at Guantanamo Bay's second war-crimes trial reached a verdict Friday that could put Osama bin Laden's alleged "media secretary" and videomaker in prison for life.

But the decision will not be announced until Monday because Ali Hamza al-Bahlul was already back in his cell at the U.S naval base prison in Cuba when the verdict was reached, said the judge, Air Force Col. Ronald Gregory.

The judge told al-Bahlul no announcement would be made in his absence.

The nine panelists, all approved by the Pentagon to serve as jurors, deliberated for roughly four hours. The accused offered no defence after calling the proceedings a "legal farce."

The prosecution said al-Balhul's violent propaganda videos helped inspire the Sept. 11, 2001, attacks on the United States.

The Yemeni prisoner also helped prepare at least two Sept. 11 hijackers for their mission and instructed many other terrorists through videos he created for al-Qaeda in Afghanistan, Army Maj. Daniel Cowhig said.

Refused to present a defence

Al-Bahul refused to present a defence in the week-long trial because the judge ruled he could not represent himself. His Pentagon-appointed lawyer did not speak at all in deference to his client's wishes, declining even to answer questions from the judge while in the courtroom.

Al-Bahul, who was brought to Guantanamo in 2002, is the second prisoner to go through a war crimes trial under the special military commissions system. He faces up to life in prison if convicted of conspiracy, supporting terrorism and solicitation to commit murder.

The military claims al-Bahlul committed war crimes by serving as chief propagandist for al-Qaeda and as an aide to bin Laden. Videos made by the defendant were allegedly shown to terrorist recruits at training camps in Afghanistan.

Cowhig said he also arranged for lead Sept. 11 hijacker Mohamed Atta to swear a loyalty oath to bin Laden, and prepared filmed martyrdom wills for Atta and fellow hijacker Ziad Jarrah in preparation for the attacks against the United States. The military says al-Bahlul repeatedly admitted to interrogators that he was al-Qaeda's media chief and made propaganda videos for bin Laden. Al-Bahlul doesn't consider his actions criminal, but the U.S. military already determined him to be an unlawful enemy combatant, and says any work he did for al-Qaeda is by definition a war crime because al-Qaeda is a terrorist organization.

Before a verdict was reached, al-Bahlul's lawyer told reporters outside the court that the government's case was surprisingly sloppy considering they had six years to prepare.

"I believe this is the last military trial that will take place. I think that this trial has further exposed this process and has turned the tide against continuing with military commissions," Air Force Maj. David Frakt told reporters

Jamil Dakwar, an American Civil Liberties Union lawyer who has been observing the trial, said the prosecution failed to prove al-Bahlul had any real connection to the Sept. 11 attacks.

"It is an injustice to the victims of 9/11 for the government to build its case solely by videos and images of the attacks," Dakwar said.

Prosecutors intend to try about 80 of the roughly 265 Guantanamo detainees, including Canadian Omar Khadr, a 21-year-old charged with killing a U.S. army medic in Afghanistan in 2002.