MIAMI - A Saudi Arabian prisoner accused of plotting the deadly attack on the warship USS Cole in 2000 could be executed if he is convicted in the Guantanamo war crimes tribunal, the Pentagon said on Wednesday.

The Pentagon official overseeing the Guantanamo trials formally approved nine terrorism, conspiracy and murder charges against prisoner Abd al-Rahim al Nashiri, and referred the case for trial by military tribunal as a capital case.

Two suicide bombers rammed an explosives-laden boat into the Cole off Yemen, blowing a massive hole in its side and killing 17 US sailors. Nashiri is accused of planning and preparing the attack, which also wounded more than three dozen sailors.

Defense lawyers argued unsuccessfully that he should not face execution because the case was tainted by torture and brutality.

Nashiri was subjected to "waterboarding" - an interrogation technique that creates the sensation of drowning - and mock executions while held at secret CIA prisons after his capture in Dubai in 2002. He was sent to the detention center at the Guantanamo Bay US Naval Base in Cuba in 2006.

The CIA has acknowledged it destroyed videotapes of Nashiri's interrogations.

"We think there were a lot of compelling reasons to say it shouldn't be a death penalty case but we're not surprised at all," said Rick Kammen, one of Nashiri's attorneys.

He called the decision a political one and said the Guantanamo tribunals, which are formally known as military commissions, were designed to render "second-class justice."

"We are disappointed the United States will now descend further down the path of expedient and secret justice that Military Commissions have come to represent." he said.

Kammen, an Indianapolis lawyer, was brought into the defense team because he has experience in death penalty cases, something most of the US military lawyers lack.

9-11 defendants could also face death penalty

Nashiri is accused of conspiring with Osama bin Laden and other al-Qaidaleaders to carry out various attacks against US targets, including the bombing of two US embassies in Africa.

The charges against him include murder, attempted murder, conspiracy, terrorism and using treachery or perfidy. The latter alleges that the Cole bombers dressed in civilian clothing and "offered friendly gestures to several crew members" in order to disguise their intent as they approached the Cole.

Nashiri is accused of plotting similar boat-bomb attacks on another US warship and a French oil tanker off Yemen.

The attack on the other warship, the USS The Sullivans, failed when the would-be suicide bombers misjudged the tide and ran their boat aground. The attack on the tanker, the MV Limburg, killed one man.

The Pentagon appointee who approved the capital charges, retired Vice Admiral Bruce MacDonald, is also weighing whether five other Guantanamo prisoners accused of plotting the Sept. 11, 2001, hijacked plane attacks on the United States should face the death penalty if convicted at Guantanamo.

Nashiri and those five defendants, who include self-described 9-11 mastermind Khalid Skeikh Mohammed, were initially charged with capital crimes during the administration of President George W. Bush.

President Barack Obama halted the trials and tried to move the cases into US federal courts but relented under pressure and put them back in the Guantanamo tribunals. Congress has blocked his attempts to shut down the Guantanamo detention camp, which holds 171 prisoners with suspected links to al Qaeda, the Taliban and other militant groups.

The war crimes tribunal has not convened at Guantanamo since February, when a Sudanese weapons trainer pleaded guilty to conspiring with al-Qaida and agreed to help the United States prosecute other captives.

Now that Nashiri's case has been referred for trial, he is expected to be arraigned at Guantanamo within 30 days.