WASHINGTON -- Terror suspects tried before military tribunals would have many of the legal rights given defendants accused of other crimes, but prosecutors could use evidence that probably would be tossed out of an ordinary American court, a U.S. official said Wednesday.

Defense Secretary Donald H. Rumsfeld was expected to announce details today about how the tribunals would operate. He has said the panels would be used in rare cases, if at all, and only if the suspects' home countries don't take over prosecution.

The Pentagon's rules seem designed to answer some of the sharpest criticism that followed President Bush's November announcement that tribunals would be an option for suspected members or supporters of the al-Qaida terror network.

A government official described the rules.

Bush said Wednesday, "The world now will begin to see what we meant by a fair system that will enable us to bring people to justice (and) at the same time protect (our) citizenry."

Asked if tribunals were imminent, Bush said, "No plans right now ... nobody in mind as yet."

In many respects, the panels would resemble criminal trials in civilian court and the parallel military system of courts-martial.

Presumed innocence

Defendants would have the right to a lawyer, for example, and the right to see the evidence against them. Military lawyers would be provided free, and defendants could hire an outside civilian lawyer if they chose. Defendants would be presumed innocent.

The panels would include three to seven officers, as do many courts-martial.

Key differences would be a freer hand for prosecutors in introducing evidence before tribunals, and a very limited right to appeal that is designed to keep defendants out of federal courts.

"I think this is falling far short of what was hoped for," said Frank Spinner, a civilian lawyer who specializes in representing military defendants before courts-martial.

The tribunals might allow prosecutors to use hearsay or evidence that came to them through unorthodox means -- for example, maps and writings discovered in Afghanistan that could have passed through several hands before U.S. investigators obtained them.

Proceedings would be largely open to reporters, although television cameras would be barred. If prosecutors wanted to present classified material, the courtroom would close.

Members of Congress were being briefed on the plan Wednesday. Several endorsed it while criticizing a lack of congressional input.

"Under ordinary circumstances, we need to have as many protections as we could possibly have," said Sen. Ben Nelson, D-Neb., an Armed Services Committee member. But, he said, the war against terrorism makes some secrecy essential, such as closing the courtroom for classified information.

Sen. Byron Dorgan, D-N.D., said he would object to tribunals only if they are used extensively. "If they're going to use them sparingly against certain al-Qaida members and others who are imprisoned, I don't have any problem with that," he said.

Nelson said the Pentagon should have sought congressional advice as it devised the plan. It was not clear whether the rules might be adjusted once Congress and other outsiders review it.