By Medina Roshan
FORT MEADE, Maryland (Reuters) - The brother-in-law of a September 11, 2001, aircraft hijacker pleaded guilty in a U.S. military court on Thursday to plotting with al Qaeda to blow up oil tankers in the Middle East.
Ahmed al Darbi, a 39-year-old Saudi, pleaded guilty at a hearing at the U.S. military prison at Guantanamo Bay, Cuba.
The plea was made to judge Air Force Colonel Mark Allred through al Darbi's attorney, Ramzi Kassem.
Captured in 2002, al Darbi had faced six charges, including attempted terrorism, terrorism and attacking civilians.
He was accused of working as a weapons instructor at an al Qaeda camp in Afghanistan in the late 1990s and of meeting al Qaeda leader Osama bin Laden there.
Al Darbi was suspected of using al Qaeda money to buy a boat and GPS navigational devices, and of helping al Qaeda operatives to obtain travel documents.
He was charged with abetting a plot to bomb civilian tankers in the Strait of Hormuz and off Yemen from 2000 to 2002. He was accused of assisting in the 2002 plot to bomb a French oil tanker off Yemen, which killed a crewman and dumped tens of thousands of gallons of oil into the Gulf of Aden.
Al Darbi was accused of working with Guantanamo detainee Abd al-Rahim al Nashiri to carry out the attacks.
Nashiri, a Saudi, is charged with masterminding the 2000 suicide bombing on the USS Cole at Aden, Yemen, that killed 17 U.S. sailors.
Al Darbi is married to a sister of Khalid al Mihdar, who helped hijack American Airlines Flight 77, which crashed into the U.S. Defense Department in 2001.
The hearing at Guantanamo Bay was transmitted via closed-circuit television to Fort Meade, an Army base outside Washington.
Nearly 3,000 people were killed in four coordinated attacks by members of al Qaeda in the worst attack on the United States in history on September 11, 2001.
(Writing by Ian Simpson; Editing by Bernadette Baum)