DUESSELDORF, WEST GERMANY, JAN. 5 -- Accused Lebanese Shiite terrorist Abbas Ali Hamadei appealed at the opening of his trial today for release of a West German hostage held in Beirut whom he is charged with having helped kidnap nearly a year ago.

Abbas Hamadei, 29, is a brother of Mohammed Ali Hamadei, who is expected to go on trial in the spring in Frankfurt for helping to stage the June 1985 hijacking of a TWA jet airliner in which a U.S. Navy diver was killed.

The U.S. administration sought unsuccessfully last year to persuade the Bonn government to extradite Mohammed Hamadei to the United States to stand trial for the hijacking. U.S. officials have said, however, that they are satisfied with West Germany's handling of the cases.

Abbas Hamadei faces up to 15 years in prison for alleged involvement in the kidnapings of two West German businessmen in Beirut in January 1987 to pressure Bonn to release Mohammed Hamadei or at least not to extradite him.

One of the businessmen, Alfred Schmidt, was released in September, three months after Bonn's decision against extradition. Reliable West German news reports, which were not denied by government sources, said Schmidt's employer, Siemens AG, and possibly other private interests had paid a ransom of at least $2 million.

Hoechst AG chemical company representative Rudolf Cordes remains a hostage.

"Although he directly or indirectly rejects the charges {against him}, he appeals to the kidnapers to release Cordes," Abbas Hamadei's lawyer, Eckhardt Hild, said.

Hild spoke after Abbas Hamadei told a five-judge panel in the heavily guarded courtroom that his lawyer was authorized to make a statement for him.

In Beirut yesterday, the group holding Cordes warned the West German government to handle the case "carefully" or risk reprisals. The trial is expected to last at least a month.

Abbas Hamadei, who has dual Lebanese-West German citizenship, was living in southwestern Germany when Frankfurt airport police caught his brother carrying four wine bottles filled with liquid explosive on Jan. 13. Mohammed Hamadei was quickly identified from his fingerprints as one of the prime suspects in the TWA hijacking.

Prosecutors will seek to prove that Abbas Hamadei agreed with accomplices within two days after his brother's arrest to kidnap a West German citizen in retaliation, according to a summary of charges presented here.

Abbas Hamadei returned to Beirut and aided in the kidnapings of Cordes and Schmidt, the summary said.

One of his accomplices was a third brother, Abdel Hadi Hamadei, it said. He is a leading security official of the pro-Iranian Shiite guerrilla organization Hezbollah.

Records of wiretaps of phone conversations held by Abbas Hamadei and persons in Beirut will be presented as evidence against him, court spokesman Klaus Forsen said.

Other evidence will include an analysis of the timing of his trips to Lebanon and of his meetings with presumed accomplices, Forsen said.

The prosecution plans to call 69 witnesses, one of them former hostage Schmidt, the spokesman said. He and U.S. officials who are following the trial said that the prosecution had prepared a strong case.

Most of today's proceedings were concerned with establishing facts about the defendant's life in West Germany before his arrest, and with presenting summaries of the evidence against him.

Police arrested Abbas Hamadei on Jan. 26 at Frankfurt airport on his return from Beirut. They discovered a cache of more than four gallons of the powerful liquid explosive methyl nitrate and 32 electrical fuses buried near his home.

Abbas Hamadei brought most of the liquid explosive to West Germany from Beirut in early January 1987, and his brother brought the rest of it, the charges said.

The defendant here faces charges of taking hostages, putting the Bonn government "under duress," and violating explosives laws.