Washington: The Pentagon on Monday charged the alleged planner of the September 11 attacks, Khalid Shaikh Mohammed, and five others with murder and conspiracy and asked that they be executed if convicted.

The charges, if approved by a Pentagon appointee who oversees the war court at Guantanamo, are the first from that court alleging direct involvement in the 2001 attacks on the United States and the first involving the death penalty.

Suspects were also charged with terrorism and violating the laws of war and targeting civilians.

“The defendants will face the possibility of being sentenced to death,” Air Force Brigadier General Thomas Hartmann told reporters.

Hartmann said the charges lay out a long-term sophisticated plan by the Al Qaida terrorist network to attack the United States of America.

"The defendants will face the possibility of being sentenced to death," Hartmann told reporters.

The attack over six years ago killed nearly 3,000 people.

Hartmann, the legal adviser to the US military tribunal system, said the six include Khalid Shaikh Mohammad, the suspected mastermind of the attacks, in which hijacked planes were flown into buildings in New York and Washington.

Another hijacked plane crashed in the fields of western Pennsylvania.

Suspects were also charged with terrorism and violating the laws of war and targeting civilians.

The military will recommend that the six men be tried together before a military tribunal. But the cases may be clouded because of recent revelations that Mohammmed was subject to a harsh interrogation technique known as waterboarding - which critics call torture.

Asked what impact that will have on the case, Hartmann said it will be up to the military judge to determine what evidence is allowed.

Prosecutors have been working for years to assemble the case against suspects in the attacks that prompted the Bush administration to launch its global war on terror.

The other five men being charged are: Mohammed Al Qahtani, the man officials have labelled the 20th hijacker; Ramzi Bin Al Shaibah, said to have been the main intermediary between the hijackers and leaders of Al Qaida; Ali Abd Al Aziz Ali, known as Ammar Al Baluchi, a nephew of Khalid Shaikh Mohammad, who has been identified as Mohammad's lieutenant for the 2001 operation; Al Baluchi's assistant, Mustafa Ahmad Al Hawsawi; and Walid Bin Attash, a detainee known as Khallad, who investigators say selected and trained some of the hijackers.

The charges against Khalid a Pakistani national better known as KSM, will include conspiring with Al Qaida to attack and murder civilians and about 3,000 counts of murder for those killed in the September 11 attacks.

Khalid also said he was responsible for a 1993 attack on New York's World Trade Center, the bombing of a nightclub in Bali, Indonesia, and an attempt to down two US airplanes using shoe bombs. He also confessed to the beheading of US journalist Daniel Pearl.