ATHENS, Greece (AP) _ Greece reneged on an extradition deal with Italy on Tuesday and deported a suspected Palestinian terrorist to Libya, his chosen destination, officials said.

The Palestinain, Abdel Osama Zomar, 27, is suspected of helping organize a September 1982 grenade attack on Rome's main synagogue that killed a 2-year- old boy and wounded 34 people.

Justice Minister Vassilis Rotis said in a statement that he overturned a 1984 agreement to extradite the Palestinian to Italy because Zomar ''was acting in the struggle for the ... independence of his country.''

In November 1984, the Supreme Court agreed to an Italian extradition request for Zomar but judicial authorities delayed carrying it out.

Western intelligence officials in Athens have said Zomar was one of three Palestinians jailed in Greece who are linked with the Palestinian terrorist faction led by Abu Nidal.

In overturning the extradition, Rotis cited the Palestine National Council's Nov. 15 declaration in Algiers. It reaffirmed the ''Cairo declaration,'' which limits Palestinian guerrilla attacks to military targets in Israel and the occupied territories.

Initially, police and Justice Ministry officials would only say that Zomar was sent to ''a country of his choice.'' But a police spokesman, speaking anonymously, said he flew to Benghazi, Libya, on an Olympic Airways flight.

Zomar has been imprisoned since November 1982, when he was arrested at the Greek-Turkish border driving a car loaded with explosives.

After serving a 20-month sentence on weapons-smuggling charges, Zomar remained in jail during a long extradition process.

In 1987, he was given an additional 20 months after prison guards found a knife in his cell.

Rotis said Premier Andreas Papandreou had been informed of the decision to free Zomar.

Last year, the government was accused of allowing the Abu Nidal group to operate a logistics office in Athens. The office was shut down in July 1987 after protests from Western allies.

U.S. counterterrorism officials have said Abu Nidal was behind a July attack on a Greek cruise ship in which nine people were killed and 98 injured.

Greek police theorized the attack was a botched attempt to take hijack the ship and force the release of three suspected Palestinian terrorists, including Zomar, held in Greece.

The others are Mohammed Rashid, 39, a Palestinian wanted by the U.S. for the 1982 bombing of a Pan Am jetliner; and Omar Mabrouki, serving a 10-year jail term for trying to shoot the Jordanian charge d'affaires in 1984.

On Nov. 15, the Supreme Court indefinitely postponed a decision to extradite Rashid, saying it wanted more documentation of his activities. Rashid was arrested May 29 at the Athens airport on a tip from the U.S. Embassy.

The Palestinian is wanted on charges of planting that killed a Japanese teen-ager and injured 15 people on a Tokyo-Honolulu flight.

Ambassador L. Paul Bremer has said the United States views Rashid's extradition as a test of Greece's determination to combat terrorism.

After the July 11 attack on the cruise ship, Papandreou's Socialist government said it still supported the Palestinian cause but warned terrorists to avoid Greece.

Greece's Western allies frequently criticized the Papandreou government for failing to act against Palestinian terrorists based in Greece.

The governing Panhellenic Socialist Movement has long retained close ties with the Palestine Liberation Organization and hardline Arab states such as Libya.