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 U.S. military jury in Guantanamo has convicted a Yemen man on war crimes charges for making propaganda videos for al-Qaeda and sentenced him to life in prison.

The nine-person jury voted to convict Ali Hamza al-Bahlul on multiple counts on charges of conspiracy, solicitation to commit murder and providing material to support terrorism.

The jury, which was composed of military officials approved by the Pentagon, reached the verdict on Friday after four hours of deliberations but only announced its decision on Monday. The sentence decision was reached later Monday, after less than an hour of deliberations.

The military has not said where he will serve his sentence.

Of the 35 counts against al-Bahlul, one count of conspiracy and one count of providing material support for terrorism were dismissed by the jury.

It is the second of such war crimes trials to be held by the special military commissions system at Guantanamo Bay, a U.S. naval base in Cuba.

The first saw Salim Hamdan, a former driver for Osama bin Laden, convicted in August and sentenced to 5½ years in prison.

Didn't mount defence

In a pretrial hearing, al-Bahlul, 39, called the military tribunal a "legal farce" and refused to mount a defence.

His Pentagon-appointed lawyer respected his wishes and stayed silent during the trial, refusing to even answer questions from the judge.

Al-Bahlul doesn't consider his actions criminal, but the U.S. military determined him to be an unlawful enemy combatant and argued any work he did was a war crime because al-Qaeda is a terrorist organization.

Prosecutors said al-Bahlul acknowledged to interrogators that he was al-Qaeda's media chief and made propaganda videos.

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

The week-long trial heard he helped at least two Sept. 11 hijackers prepare for their mission, filmed martyrdom wills and instructed other terrorists through videos he created for al-Qaeda.

Breaks silence

As the post-trial hearing began on Monday afternoon, al-Bahlul broke his silence briefly to tell the judge he would not be making a statement before he was sentenced.

"Go ahead with your trial and I will continue with my boycott. You do whatever you want," al-Bahlul said through an Arabic translator. "You have orders from the politicians, and I will not accept it."

But as testimony at the post-trial hearing, including testimony from the father of a sailor killed in the 2000 attack on the USS Cole, al-Bahlul became agitated.

Al-Bahlul told the court the United States had oppressed Muslims for more than 50 years.

"We will fight any government that governs America," he told the military jurors at the sentencing hearing. "We are the only ones on Earth who stand against you."

He also said the U.S. had only itself to blame for the Sept. 11 attacks. "Whoever said this happened out of nowhere is an idiot," he said. "You have started the war against us."

Al-Bahlul was brought to Guantanamo in 2002.

With files from the Associated Press and Reuters