NICOSIA, Cyprus (AP) _ A Briton and two Palestinians admitted in court Friday that they murdered three Israelis on a yacht in September. They claimed their victims were spies responsible for the deaths of many Palestinians.

Israel says the murder victims were tourists, members of a Haifa yacht club.

The confessions came on the fifth day of the trial, in which each defendant faces three separate murder charges for the killings Sept. 25 in the marina at Larnaca, Cyprus.

The triple slaying triggered a cycle of retaliatory violence. Israel, blaming the Palestine Liberation Organization for the Cyprus killings, sent its warplanes to bomb PLO headquarters in Tunisia on Oct. 1. About 60 people were killed.

One week later, Palestinian guerrillas hijacked the Italian cruise ship Achille Lauro. An American passenger was shot to death and thrown overboard before the hijackers surrendered.

At the Nicosia trial, a Palestinian defendant whose Syrian passport identifies him as Khaled Abdel-Kader el-Khatib, 28, said: ''We killed the Israelis because they ran a spy ring in Cyprus and were responsible for the arrest of many of our comrades as well as the murder of many women and children.''

The defendant told the court his real name was Elia Yahia Nassif.

Speaking in Arabic, through an interpreter, he added: ''They also killed my former boss, Ali Hassan Salama Abu Hassan.''

Ali Hassan Salama, known by his code name Abu Hassan, was a senior PLO intelligence officer. He was generally regarded as the mastermind of several attacks in the 1970s, including the killing of Israeli sportsmen at the 1972 Summer Olympics in Munich, West Germany.

Abu Hassan was killed by Israeli agents in Beirut, Lebanon, in 1979.

The three Israelis shot dead on their yacht were Reuven Palzur, 53; his wife Esther, 50, and Abraham Avnery, 55.

In earlier testimony, the defendants said the Israelis were watching the movements of Palestinian guerrillas traveling by sea from Larnaca to Lebanon. They claimed the information supplied helped Israel to stop many Palestinians en route.

The other Palestinian accused, whose Jordanian passport identifies him as Abdel-Hakim al-Khalifa, 29, admitted shooting Mrs. Palzur.

Ian Michael Davison, 28, a carpenter from the north England town of Southshields, said: ''I have no regrets for doing what I have done because it was my duty as an international socialist and a person of conscience to fight the Zionist movement wherever I can.''

Davison and the Palestinian who gave his name as Nassif each admitted killing one of the Israeli men.