The federal judge presiding over the hijacking case of alleged Lebanese terrorist Fawaz Yunis yesterday threw out a written confession and all other statements Yunis made to FBI agents shortly after his arrest, ruling that during their "relentless questioning" the agents had violated Yunis' constitutional rights.

"These constitutional principles should not be cast aside nor minimized merely by invoking 'national security' or 'the fight against terrorism,' " U.S. District Court Judge Barrington D. Parker said. His strongly worded 47-page opinion repeatedly rebuked FBI officials for the way Yunis was treated after he was arrested last September in international waters off Cyprus.

Parker said Yunis was not properly advised of his rights in a way he could understand; did not receive adequate medical treatment for the broken wrists he sustained while being arrested; was questioned for more than nine hours without the knowledge or approval of doctors treating him for seasickness, and was not provided an attorney during questioning.

Parker was especially critical of the delay between Yunis' arrest and his arraignment here before U.S. Magistrate Jean F. Dwyer, ruling that it "appeared to serve only the government's purposes -- ample time to educe a confession."

An FBI spokesman said yesterday that the bureau would not comment on Parker's ruling or Yunis' arrest on Sept. 13.

Yunis, 28, was wanted in connection with the 1985 hijacking of a Royal Jordanian jetliner from Beirut International Airport. The plane was blown up after passengers and crew were taken off. Yunis, at the time of the hijacking a member of the Amal militia, was arrested at sea after he was lured by a former associate onto the "Skunk Kilo," an FBI-operated yacht, with promises of a lucrative drug deal.

The FBI operation was planned and carried out under the direct supervision of Oliver B. Revell, the bureau's executive assistant director of investigation. Parker based his opinion on a description of the arrest provided by Revell during earlier testimony, but did not name Revell in his criticisms.

The operation and most planning for it occurred between the time William H. Webster was nominated to head the Central Intelligence Agency and William S. Sessions replaced him as FBI director.

It was unclear yesterday if Parker's ruling will delay Yunis' trial, set for March 22. The government, which has a wealth of other evidence that Yunis was the ringleader of the hijackers, can appeal Parker's decision only if prosecutors can show that exclusion of the statements and confession cripples their case.

A spokesman for the U.S. attorney's office said prosecutors and Justice Department officials are reviewing the ruling.

Francis D. Carter, Yunis' court-appointed attorney, said that in "15 years of practicing law, this case had the strongest factual basis for the suppression of statements. I'm glad the court recognized all the appropriate elements."

But Carter said he was "disappointed" that Parker denied his request to dismiss the indictment because of illegal arrest.

Carter said yesterday that he believes his client's name should be spelled Younis, but court papers spell it without the "o."

In his ruling, Parker said that both of Yunis' wrists were broken as a result of the "aggressive and forceful arrest" by FBI agents, who threw him to the yacht's deck after he was lured on board.

About an hour later, Yunis was transferred to a naval ordnance ship, the USS Butte, where he was kept for four days as it steamed 2,000 miles to an aircraft carrier. From there, he was taken on a 13-hour flight to Andrews Air Force Base.

Parker ruled that although Yunis complained about his wrists immediately after his arrest, he was not given even a cursory examination until the next day and his wrists were not X-rayed until he reached the United States.

Doctors who examined Yunis aboard the Butte recommended rest to combat Yunis' seasickness and weakened condition, but he was questioned several times during the four days without the physicians' knowledge, Parker said.

Yunis was advised of his rights against self-incrimination only at the beginning of the first interrogation session, and Parker said that was done with an incorrect translation and in a way that Yunis, unfamiliar with U.S. rights, could not have fully understood.

Parker said Yunis should have been provided an attorney throughout all questioning, and that the FBI "missed an excellent opportunity" to show that the statements were made freely by not videotaping or recording the questioning.