A chaotic three-month trial ended Saturday with the convictions of 15 men accused in terror attacks on a French oil tanker and a helicopter carrying U.S. oil workers, as well as plots to kill the U.S. ambassador and Yemeni security officials.

One of the defendants, convicted of killing a Yemeni police officer, was sentenced to death. The others received from three to 10 years in jail. One man was tried in absentia.

"There is no god but Allah, America is the enemy of Allah, Osama is beloved by Allah," the defendants chanted from their court cells, referring to Osama bin Laden. Some of the men are believed to be linked to bin Laden's al Qaeda network.

The trial, which began May 29, centered on the October 2002 bombing of the French oil tanker Limburg off the Yemeni coast. Two suicide bombers rammed an explosive-laden boat into the vessel, killing a Bulgarian crew member and spilling 90,000 barrels of oil into the Gulf of Aden -- an operation very similar to the attack on the American destroyer USS Cole off Yemen's coast two years earlier.

The defendants accused authorities of not following proper procedures during the trial and of undermining their rights.

Fayez Hajoury, an attorney for one of the defendants, described the verdicts as "null and void," saying the work of defense attorneys was obstructed by authorities.

"We never got a chance to get hold of the files of the case," which contain evidence, investigations and interrogations, he said.

The defendants said they would appeal the verdicts and sentences.

Judge Ahmed Jarmouzi sentenced six defendants to 10 years in prison for participating in the Limburg bombing.

Also sentenced to 10 years was Yasser Ali Salem, who is at large. Salem was believed to be a key plotter of the Limburg attack and to have been in charge of buying and delivering the explosives used by the suicide bombers.

Hazam Majali was sentenced to death after being convicted of killing a Yemeni police officer at a checkpoint in 2002.

Six others were sentenced to five years in jail for detonating explosives at embassies, plotting to assassinate U.S. Ambassador Edmund Hull and security officials, and playing roles in an attack on a helicopter carrying U.S. employees of the Texas-based Hunt Oil Co. in November 2002.

Another defendant was sentenced to three years in prison for falsifying documents relating to the various attacks.

In issuing his verdict, the judge cited the defendants' confessions that Saudi-born Rahim Nashiri, an alleged mastermind of the USS Cole attack, gathered funds for the Limburg operation.

Qassim Yahya Raimi was convicted of taking part in a plot to kill the U.S. ambassador to Yemen and attack foreign embassies.