"They are not my lawyers, I am al-Qaida, they do not represent me," the 37-year-old Frenchman said minutes after entering the federal courtroom in the Washington suburb of Alexandria.
"This trial is a circus," he added.
The outburst came as the first group of prospective jurors gathered to answer a questionnaire that will be used to help the judge and the lawyers select 12 jurors and six alternates.Moussaoui - the only person charged in the United States in connection with the 9/11 hijacked airline attacks that killed about 3000 people - pleaded guilty last April to all six counts against him.
That is expected to take a month, setting the stage for the trial to begin on 6 March on whether Moussaoui will be put to death or given life in prison.
The jury will now decide if he gets the death penalty or life in prison.
Nearly 3000 Americans died when 19 hijackers crashed four airliners into New York's World Trade Centre, the Pentagon and a Pennsylvania field.
Last April, against advice from his court-appointed attorneys, Moussaoui pleaded guilty to six conspiracy counts.
Nearly 3000 people died in the
September 11 terrorist attacks
He admitted he "knew of al-Qaida's plans to fly airplanes into prominent buildings in the United States and he agreed to travel to the United States to participate in the plan".
During the terror attacks, Moussaoui was in jail in Minnesota on immigration charges, having aroused suspicion while training to fly Boeing 747 jumbo jets.
And he claims he knew nothing of the 9/11 plot.
Instead, Moussaoui told Brinkema, he had been ordered by al-Qaida leader Osama bin Laden to learn to fly a 747 into the White House as part of a different plot if the US refused to release Shaikh Omar Abdel Rahman, an Egyptian cleric.
Rahman is serving life for crimes related to the 1993 World Trade Centre bombing and 1995 plots against New York landmarks.
Vow to fight
Moussaoui vowed "to fight every inch against the death penalty".
Once 12 jurors and six alternates are picked for the sentencing trial, opening statements are set for 6 March.
The trial could last one to three months.
The jurors will be asked to decide first whether what Moussaoui acknowledged qualifies for the death penalty and then, if so, whether he deserves it.
If either answer is no, he will get life in prison.