Amnesty International has taken up the cause of a Guantanamo prisoner who is said to be in declining health as he awaits trial for his alleged role in the Sept. 11, 2001, terrorist attack.

Image has been reviewed by the U.S. Military prior to transmission.) U.S. Marines conduct a road march in the early morning in Guantanamo Bay, Cuba.(Photo by Joe Raedle/Getty Images)

The rights group is asking the Defense Department to investigate claims by lawyers for Mustafa al-Hawsawi that he is receiving inadequate medical treatment at the U.S. base in Cuba.

The letter released by the Saudi prisoner's lawyers Wednesday also calls for a full review of all medical care at Guantanamo as well as treatment for injuries his lawyers say were sustained while in CIA custody from 2003 until he was taken to the base in Cuba in September 2006.

"He is reported to be suffering chronic and potentially life-threatening illness, and he requires appropriate and ongoing medical assessment and treatment," said the letter from Margaret Huang, interim executive director of Amnesty International USA.

A Pentagon spokesman, Navy Cmdr. Gary Ross says all detainees receive the same treatment as soldiers but said the government cannot discuss the medical condition of any individual.

Al-Hawsawi and four co-defendants are due in court next week for a pretrial hearing in their long-stalled case.

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