Mohammed Ali Hamadi admitted in court Tuesday to being one of four men who hijacked a TWA jetliner to Beirut in 1985, but denied shooting to death a U.S. Navy diver during the ordeal.

"I took part in the hijacking," the Lebanese Shiite Moslem said, reading from a statement in the heavily guarded courtroom."If this act which I committed is against the law, then it is a result of illegal conduct on the part of Israel," Hamadi, speaking in Arabic, said through an interpreter.

Thirty-nine Americans were held captive for 17 days after TWA Flight 847 was hijacked on an Athens-to-Rome flight. During the ordeal, Navy diver Robert Stethem was killed and his body thrown onto a Beirut airport runway.

Hamadi, on trial for air piracy and murder, said he hijacked a U.S. aircraft "because the United States is the greatest ally and supporter of Israel."

Clean-shaven and wearing an open-neck cream-colored shirt, Hamadi read calmly and clearly from the statement.

He said the goal of the June 1985 hijacking was to gain freedom for Shiite Moslems imprisoned in Israel.

"The decision to hijack the plane came after everything else failed," Hamadi said in the 45-minute presentation. "There was no other way to free the prisoners other than the means chosen."

Shortly after the June 1985 hijacking ended, Israel released approximately 700 Shiites.

Until Tuesday, the only testimony that Hamadi was involved in the hijacking came from two witnesses who testified that Hamadi's older brother Abbas had told them as much.

Hamadi told the court that one of the three alleged hijackers still at large, Hassan Iz-al-Din, was in charge of the hijacking and had shot Stethem.

"The pistol was in his (alleged hijacker Hassan Iz-al-Din's) hand," Hamadi said. "I didn't use it. Our orders were not to harm anyone, but I couldn't convince him not to shoot."

Stethem's parents, Richard and Patricia Stethem of Waldorf, Md., were sitting in the courtroom as Hamadi spoke.

When Hamadi finished, Chief Judge Heiner Mueckenberger said the testimony "was surprising for everybody. It marks a certain turn in the trial."