WASHINGTON: The man accused of plotting the September 11 attacks, Khalid Sheikh Mohammed, and two of his accomplices held at the Guantanamo prison have agreed to plead guilty to conspiracy charges in exchange for a life sentence, the New York Times reported on Wednesday citing unidentified Pentagon officials.

The deal for the guilty pleas by Mohammed, Walid Bin Attash and Mustafa al-Hawasawi rather than a death penalty trial has been approved by a senior Pentagon official, the Times said.

All three men have been in custody since 2003. Mohammed is an al Qaeda militant accused by the US of being the principal architect of the September 11 attacks on New York's World Trade Center and the Pentagon outside Washington.

"In exchange for the removal of the death penalty as a possible punishment, these three accused have agreed to plead guilty to all of the charged offenses, including the murder of the 2,976 people listed in the charge sheet," the chief prosecutor, Rear Admiral Aaron Rugh, said in a letter to family members of September 11 victims, according to the Times.

The letter said the men could submit their pleas in open court as early as next week, according to the Times.The Defense Department released a statement on Wednesday saying prosecutors had reached plea agreements with Mohammed, Bin Attash and al-Hawasawi, without disclosing the terms of those deals.