Fort Meade - A Yemeni accused of the September 11 attacks walked out of a courtroom at Guantanamo Bay on Tuesday, claiming that the lack of food he received amounts to "psychological torture".
Ramzi Binalshibh, one of five men on trial over the hijacking and crashing of airliners that killed almost 3 000 people in the United States in 2001, said after lunch that he could not continue under the circumstances.
"I cannot remain here. There are big problems with the food provided. This is a daily practice... when I go to hearings and I go to meetings with my lawyer, they don't bring us food," he said in Arabic, which was translated.
"This is one type of psychological torture," added Binalshibh, the only suspect to appear on Tuesday, the second day of the latest preliminary hearing broadcast via a video link to a US military base at Fort Meade, in Maryland.
Self-declared 9/11 mastermind Khalid Sheikh Mohammed - wearing camouflage garb and his beard tinted with henna - appeared in the military court at the US prison in Cuba with his four co-defendants on Monday.
All face the death penalty if convicted of plotting the attacks on New York and Washington. Preliminary hearings in the case began in May 2012.
Binalshibh, wearing a white robe and a traditional Arab headdress, said that the problems over food applied not just to him but to "my brothers as well".
A military spokesperson, US Naval Captain Robert Durand, said Binalshibh had been provided with a freshly-prepared standard detainee halaal meal during the court hearing's lunch recess.
"The defendant complained that his lunch did not include condiments such as olives and honey," Durand added.
Binalshibh's lawyer, Jim Harrington, said his client felt that the conditions at the US Naval Base in Cuba "have been made intolerable for him".
"Sometimes little things - not so little - built up, built up, and built up, things become even bigger," Harrington said.
US military judge James Pohl had told Binalshibh that if he chose to leave the afternoon session the suspect must acknowledge he was making "a voluntary choice, a personal decision," and he received a "yes," in reply.
Kevin Bogucki, Binalshibh's other lawyer, said the case had no precedent in American history due to how the detainees are treated.
He noted the "frustration" of his client, whose cell he said was subjected to "noises and vibrations that interfere with his ability to concentrate, to sleep," he said.
Chief prosecutor General Mark Martins said there was nothing to back up those claims.
The five defendants were held incommunicado in secret CIA prisons from 2002 to 2006, before they were transferred to Guantanamo.
The detainees' treatment has come under close scrutiny. Mohammed is known to have been subjected to 183 sessions of water boarding, the technique of simulated drowning that has been decried as torture by rights groups.
"Torture is a mitigating factor in this case because it's a death penalty case," said David Nevin, Mohammed's lawyer.