|Mohammed is being held with several other 9/11 accused in the US-run Guantanamo Bay prison facility [GALLO/GETTY]
US military prosecutors in the Guantanamo Bay tribunals have filed new conspiracy and murder charges against five men accused of plotting the September 11, 2001, attacks.
The charges, filed on Tuesday, accuse Khalid Sheikh Mohammed, the self-described 9/11 mastermind, and four alleged co-conspirators of conspiring with al-Qaeda to carry out the attacks in which almost 3,000 people were killed.
The prosecution has requested that the men, who are all being held in the US prison facility in Guantanamo Bay in Cuba, be executed if convicted.
Bruce MacDonald, a retired vice-admiral who is overseeing the Guantanamo tribunals, will decide whether the case will proceed to trial and whether the death penalty should apply.
In addition to Khalid Sheikh Mohammed, who was captured in Pakistan in 2003, the defendants include Ali Abdul Aziz Ali, his nephew, as well as Walid bin Attash, Ramzi Binalshibh and Mustafa al Hawsawi.
A letter sent to families of 9/11 victims lists the charges as: "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 five faced similar charges during the administration of George Bush, the former US president.
But those charges were dropped while Barack Obama, the current US president, tried to move the trials to a civilian court in New York, close to the site of the World Trade Centre, which was destroyed in the attacks.
Obama yielded to political opposition to the move and in April announced that the prosecutions would be moved back to Guantanamo.
Human rights activists have criticised Obama for failing to make good on his promise to shut the Guantanamo detention centre.
However, Obama has seen his approval ratings on national security rise since he authorised the military raid that killed Osama bin Laden, the al-Qaeda leader, in Pakistan in early May.
Hearings could begin around the time of the 10th anniversary of the attacks.