BERLIN (AP) _ Police today arrested a West German woman suspected of planting a bomb in a West Berlin discotheque that killed two U.S. soldiers, prompting the United States to attack Libya.

The government said Christina Gabriele Endrigkeit, 27, who allegedly was working for two Palestinian terrorists in the April 5, 1986 bombing, was arrested along with an unidentified man in the northern port city of Luebeck.

The blast in the crowded La Belle club, which was popular with American soldiers, also killed a Turkish woman and injured 229 people.

Mrs. Endrigkeit disappeared after the bombing and was believed hiding with her 3-year-old son. On Sunday, Volker Kaehne, spokesman for the West Berlin Justice Department, released a photograph of her and told reporters she was being ''urgently sought'' as a key suspect in the case.

The arrest, first reported by Radio Schleswig-Holstein, was confirmed by Monika Stenkat, spokeswoman for the Schleswig-Holstein state Interior Ministry.

Kaehne said Mrs. Endrigkeit was arrested at 2:40 a.m. He said she would soon be brought to West Berlin and be questioned this week about her role in the bombing.

The United States blamed Libya for the La Belle attack and 10 days later bombed Tripoli and Benghazi in retaliation for it and other acts of terrorism it said Libyan leader Col. Moammar Gadhafi had aided. Western diplomats said at least 100 people were killed.

Authorities always have believed there was an Arab connection in the La Belle bombing, with Libya and Syria most suspect, West German security sources said today. They spoke on condition of anonymity.

One source said discussion of foreign involvement would have to wait for further investigation now that Mrs. Endrigkeit has been arrested.

Spokesman Robert Heath of the U.S. Embassy in Bonn today declined comment on whether new developments in the case would have any effect on the U.S. insistence Libya was behind the La Belle bombing.

U.S. authorities said after the bombing that they had intercepted radio messages from the Libyan embassy in East Berlin that implicated Gadhafi's agents in the attack. West German investigators have said they never were given any such evidence.

Chancellor Helmut Kohl and other West German officials also said shortly after the disco bombing that Libya was suspected of orchestrating the blast.

On Sunday, a security source said Mrs. Endrigkeit was believed to be in hiding with her 3-year-old son, Michael. The source, who also spoke on condition of anonymity, said Mrs. Endrigkeit ''allegedly acted (in the bombing) on behalf of the Jordanian-born brothers Ahmed Nawaf Hasi and Nezar Hindawi.''

Hasi is serving a 14-year prison sentence for his convicted in the March 1986 bombing of West Berlin's German-Arab Friendship Society building, which injured nine people. His accomplice, Farouk Salameh, was sentenced to 13 years in prison.

Kaehne said Sunday that Hasi remained a suspect in the La Belle bombing.

Hindawi, who adopted the surname of a prestigious clan in northern Jordan, is serving a 45-years prison term for trying to blow up an Israeli airliner in April 1986. The plot was foiled when explosives were found in the hand luggage of his pregnant Irish girlfriend.

Hasi was arrested two weeks after the La Belle attack and police found what appeared to be drawings of the discotheque in his possession.

A West Berlin court ruled that the friendship society attack was plotted by Hindawi and Syrian intelligence officials. Hindawi's trial in London also disclosed a Syrian connection.

Testimony at Hasi's trial indicated he went to Libya in July 1985 with Hindawi, who was seeking financial support for a terrorist group. After failing to obtain money from Libyan authorities, Hindawi went to Syria in search of backing, court papers show.

British intelligence sources have said Hasi flew from Germany to Tripoli with Salameh in February 1986 and met Hindawi there. However, the Libyans apparently were not helpful and Hindawi and Salameh later flew to Damascus, Syria, the intelligence sources said.

Killed in the disco bombing were Sgt. Kenneth Terrance Ford, 21, of Detroit, Staff Sgt. James E. Goins, 26, of Ellerbee, N.C., and a Turkish woman, 28-year-old Nermine Hanay. Ford and Ms. Hanay died immediately. Goins died of his wounds June 7, 1986, in a West Berlin hospital.