One of five men accused of plotting the September 11, 2001 attacks was expelled from a Guantanamo courtroom Monday after trying to speak without permission.

The incident involving Yemeni Ramzi Binalshibh happened shortly after the start of a new round of preliminary hearings at the US military facility in Cuba.

"I have the right to talk," Binalshibh said in English after the presiding military judge, Colonel James Pohl, asked the suspects if they understood their rights to waive their right to be present at the start of the proceedings broadcast to Fort Meade near the US capital.

"No you don't have the right to talk," Pohl countered before deciding to temporarily expel the detainee.

"He was warned not to be disruptive," Pohl said, adding that Binalshibh's conduct justified his exclusion.

Investigators say Binalshibh would have been on one of the hijacked planes that smashed into US buildings on 9/11 had he not failed to get a visa granting him entry to the United States.

Binalshibh, allegedly a member of Al-Qaeda's German-based Hamburg cell which planned and carried out the attacks, was captured in Karachi in September 2002 before being handed over to US officials.

Self-declared 9/11 kingpin Khalid Sheikh Mohammed, donning camouflage and sporting a red-tinted beard, also tried to speak about his incarceration at Guantanamo's secretive Camp 7.

Camp 7 is the most secure part of Guantanamo.

"We are never allowed to get any paper from our lawyers," he said in Arabic comments that were translated into English. He was subsequently also cut off by the judge.

But Mohammed, the translation of whose comments became inaudible, was not expelled.

David Nevin, Mohammed's lawyer, told the judge that his client feared that failure to meet with his defense counsel could negatively affect his case.

The proceedings, expected to continue until Friday, were suspended until Wednesday morning because a defense lawyer became ill.

The five accused face the death penalty if convicted of plotting the attacks 12 years ago on New York and Washington, which left nearly 3,000 people dead. A date for their trial has not been set. The preliminary hearings began in May 2012.