WASHINGTON — President Bush has designated six prisoners to become the first terrorism suspects who could be tried before military tribunals, the Pentagon announced Thursday.

Officials refused to identify the six suspects being held in U.S. custody. All are believed to be either members of the al-Qaida terrorist network or otherwise involved in terrorism, said two Pentagon officials who briefed reporters on condition of anonymity late Thursday.

Some of the six may have attended terrorist training camps, and some were involved in raising money and recruiting for terrorist groups, the officials said. Under Bush's order creating the military tribunals, only people who are not U.S. citizens can be subject to such trials.

The next step is for a chief prosecutor to draft charges against any or all of the suspects.

Deputy Defense Secretary Paul Wolfowitz will then make a separate decision on whether the suspects will actually face trials by what the Pentagon calls military commissions.

The United States might not publicly identify the suspects even if they go to trial, a senior Defense Department official told reporters. None of the officials who discussed the matter Thursday would say where the suspects are being held, though all are in U.S. custody.

Australian detainee David Hicks, who is being held at the U.S. Navy base in Guantanamo Bay, Cuba, likely will be one of the six, said his lawyer, Stephen Kenny.

Kenny said he did not know why the 26-year-old Hicks was chosen. "Whether (it is because) he is one of the most dangerous men in Guantanamo Bay, we would say that is extremely unlikely," he said. "It could be that he is someone who has attracted publicity."

Hicks, a Muslim who fought with the Kosovo Liberation Army, called his parents 17 days after the Sept. 11 attacks to say he was with the Taliban. He also allegedly threatened to kill an American upon his arrival at Guantanamo, U.S. officials said.

The Pentagon officials also raised the possibility that the military might continue to hold the suspects even if they are acquitted by a tribunal. The prisoners' status as "unlawful combatants" in the war against terrorism is separate from their guilt or innocence on charges brought before a tribunal, a military official involved in the tribunal process said.

Unlike traditional criminal trials, the proceedings of military tribunals can be kept much more secret. The United States has not convened such a tribunal since World War II.

The prospect of secret trials drew criticism from the chairman of the American Bar Association's task force on the treatment of detainees in the war on terrorism.

"The State Department issues a report every year in which it criticizes those nations that conduct trials before secret military tribunals," said Neal Sonnett, also a former president of the National Association of Criminal Defense Lawyers. "What I'm hearing sounds alarmingly like something similar."

"If they're going to be charged by military tribunals then they have a right to full due process."

Initial criticism of the administration's intent to use such trials was later tempered — but only somewhat — when the detailed rules governing them were released. Under those rules, defendants have many traditional legal rights, though they still do not have full constitutional protection, and the standards of evidence are looser.

Although the six are the first to be declared subject to trial by tribunal, Bush could designate more suspects for possible military trials. The United States will continue to gather intelligence information for the war on terrorism from the suspects up to and during their trials, the Pentagon officials said.

Candidates for the tribunals include the 680 or so terrorism suspects being held at Guantanamo. Officials there have begun planning for construction of trial facilities and even an execution chamber, since the tribunals would be able to consider imposing the death penalty.

Terrorist suspect Zacarias Moussaoui is among those who have been talked about as a possible prospect for such a trial.

A U.S. District Court judge has ruled that, as part of his criminal trial, Moussaoui could question Ramzi Binalshibh, suspected organizer of the Sept. 11, 2001, terror attacks. Arguing that questioning could harm national security, the government is appealing that ruling. But if it loses, it could decide to move Moussaoui's case from civilian court to a military tribunal.

Binalshibh is another captive who has been mentioned as a possibility for a military tribunal.

Pentagon rules for the tribunals list 18 war crimes and eight other offenses, including terrorism and the deliberate killing of civilians, that could be handled by the military commissions. The cases would be decided by a panel of three to seven military officers who would act as both judge and jury. Convictions could be handed down by a two-thirds vote; a decision to sentence a defendant to death would have to be unanimous.

All defendants would be given military defense lawyers who would be able to attend any closed hearings discussing classified information. The defendants and their private, civilian lawyers could be excluded from secret hearings. As in regular U.S. military court, the government would not pay for a defendant's civilian lawyers.

Critics say the rules for the tribunals, particularly their secrecy, give prosecutors an unfair advantage.

"It's a Draconian system of justice that is almost guaranteed to get convictions, including a possible death penalty," Michael Ratner of the Center for Constitutional Rights said Thursday.