MIAMI: US military prosecutors filed new conspiracy and murder charges on Tuesday against five men accused of plotting the Sept. 11 attacks in 2001 and asked that they be executed if convicted in the Guantanamo war crimes tribunals.

Self-described 9/11 mastermind Khalid Sheikh Mohammed and four alleged co-conspirators were charged with conspiring with al Qaeda to carry out the attacks that killed nearly 3,000 people in the United States.

All are being held in a high-security prison at the US naval base in Guantanamo Bay, Cuba.

All five faced similar charges at Guantanamo during President George W. Bush's administration. The charges were dropped while President Barack Obama's administration tried to move the trials into federal civilian court in New York, near the site of the World Trade Center, which was destroyed in the attacks by hijacked aircraft.

Obama yielded to political opposition and announced in April the prosecutions would be moved back to Guantanamo.

Human rights activists have criticized Obama for failing to make good on his order to shut the Guantanamo detention camp.

But his approval ratings on national security issues have risen since he authorized the military raid that killed al Qaeda leader Osama bin Laden in Pakistan in early May.

The official overseeing the Guantanamo tribunals, retired Vice Admiral Bruce MacDonald, must decide whether the case will proceed to trial and whether the death penalty should apply.

Hearings could begin around the time of the 10th anniversary of the attacks.

In addition to Mohammed, an al Qaeda leader captured in Pakistan in 2003, the defendants include his nephew Ali Abdul Aziz Ali as well as Walid bin Attash, Ramzi Binalshibh and Mustafa al Hawsawi.

They are charged with conspiracy, murder in violation of the law of war, attacking civilians, attacking civilian objects, intentionally causing serious bodily injury, destruction of property in violation of the law of war, hijacking aircraft and terrorism.

“The prosecutors have recommended that the charges against all five of the accused be referred as capital,” the Pentagon said in a news release, referring to plans to seek the death penalty.

During a pretrial hearing at Guantanamo in 2008, all five said they wanted to plead guilty. The charges were dropped before the military judge could determine whether they were all mentally competent to make that decision and whether the murky tribunal rules allowed them to be executed without a jury verdict on their guilt.