Updated

A Yemeni court on Monday sentenced six Al Qaeda militants to death after convicting them in a string of attacks last year, including a deadly assault on the U.S. Embassy and a shooting that killed two Belgian tourists.

The court sentenced 10 other militants, including four Syrians and a Saudi, to up to 15 years in prison for masterminding the attacks.

The 16 defendants were crammed into a cage during Monday's sentencing. They shouted insults at the judge after he read the verdict, calling him an "infidel" and chanting Islamic prayers. "We will free the land of Islam, from Yemen to Iraq; God is great," they shouted.

One of the defendants, Mohammed Khalil, a Syrian who received 15 years in prison, shouted from behind the bars that "this is not fair." Fifteen of the suspects, including Khalil, rejected defense lawyers, choosing instead to represent themselves.

Authorities say the men were members of a cell that attacked the U.S. Embassy in March 2008, killing a school guard in an adjacent building. They also killed two female Belgian tourists in January 2008.

In addition to foreign targets, the militants were accused of waging successive attacks on police headquarters in the southeast city of Sayoun, killing one policeman and wounding 17 others in July 2008. The militants also targeted a Chinese company and an oil refinery in the southern port city of Aden during the same period.

Following the ruling, Yemen's Interior Ministry said it was beefing up security around foreign diplomatic missions and foreign commercial interests. It said the moves were "preventive measures" to avoid any "terrorist attacks" on foreign interests, though it didn't explicitly link the security upgrade to Monday's verdicts. Security was tight around San'a Monday and additional security checkpoints were erected during the day around the court house and in other areas of the city.

Yemen is a U.S. ally in the global fight against terror, but it has also been the site of numerous high-profile, Al Qaeda-linked attacks, including the 2000 bombing of the USS Cole in the Gulf of Aden, which killed 17 American sailors. Most recently, an attack on the U.S. Embassy last September killed 19 people. Yemen is the ancestral homeland of Usama bin Laden.

Most of the 16 militants convicted Monday were arrested last August following a fierce gunbattle between Al Qaeda militants and Yemeni security forces in the southern province of Hadramut. When Yemeni police ambushed their homes, explosives, RPG and other weapons were confiscated, and a local Al Qaeda leader was killed.

Yemen's government struggles to maintain order but many areas of the severely impoverished country are beyond government control, and Islamic extremism is strong.