BONN, JUNE 22 -- West German government sources confirmed today that Bonn plans to reject a five-month-old U.S. request to extradite an accused Lebanese terrorist and that the suspect instead will be tried in this country for murder, hijacking and plotting to cause an explosion.

U.S. Attorney General Edwin Meese III, who arrives here Tuesday for a one-day official visit, will make a final appeal for the extradition of Mohammed Ali Hamadei, U.S. officials said.

But the West German sources said that the decision against extradition already has been made. The government is convinced that extraditing Hamadei would endanger the lives of two West German businessmen held in Lebanon by kidnapers seeking Hamadei's release, the sources said.

As a result, Meese's discussions are likely to focus on how the U.S. government can provide West Germany with evidence against Hamadei needed to try him here for murder and air piracy, western diplomatic sources said.

{President Reagan said, "Yes," when asked Monday while on a speechmaking trip to Melbourne, Fla., if he would be satisfied if Hamadei were tried in West Germany rather than extradited, The Associated Press reported. "I knew and have known that he's going to be tried for murder wherever he's tried," the president said.}

Hamadei allegedly was one of the terrorists who staged the June 1985 hijacking of a TWA jet airliner to Beirut. U.S. Navy diver Robert D. Stethem of Waldorf, Md., who was one of the passengers, was murdered during the hijacking.

The Bonn government's decision, which will be announced on Wednesday after a Cabinet meeting, is expected to cause some strain in U.S.-West German relations. The U.S. Senate approved a resolution on Friday urging Bonn to extradite Hamadei.

A West German official predicted, however, that Washington's irritation would be "manageable." The United States has said that it would "strongly prefer" to have Hamadei tried in the United States, but U.S. officials have said that they would be satisfied as long as he faced the same charges of murder and air piracy in West Germany as he would in the United States.

If convicted of murdering Stethem, Hamadei would face a mandatory life sentence with the possibility of parole after 15 years. Senior West German officials have indicated that they do not expect him to be pardoned after serving only a short time in jail in order to win the West German hostages' release, but West German press reports have said that such a deal remains possible.

Bonn's decision against extradition has been expected since June 10, when White House spokesman Marlin Fitzwater said that Chancellor Helmut Kohl had rebuffed a personal appeal from Reagan at the Venice economic summit to extradite Hamadei.

Fitzwater said that Kohl indicated clearly that Hamadei would be tried in West Germany, but the Bonn government said the next day that a final decision had not been taken. The delay apparently was due to the need to reach a formal agreement within Kohl's coalition government and to Bonn's desire to make one last try at achieving the release of the West German hostages, according to government and diplomatic sources.

West German police arrested Hamadei in January when he was caught at the Frankfurt airport smuggling liquid explosive into West Germany. He was identified from his fingerprints as one of four men wanted in the United States for participating in the 17-day TWA hijacking, according to West German and U.S. officials.

American victims of the hijacking, who were brought to West Germany a week ago and asked to identify Hamadei, testified formally before West German legal authorities that he was one of the hijackers, according to informed sources.

The sources, who confirmed West German media reports, said that there were "no problems" with the identification session. The Americans' testimony is expected to play a key role in West Germany's case against the suspect.

Immediately after Hamadei's arrest, the Bonn government expressed the desire to extradite him quickly to the United States. It changed its mind, however, after the abductions in Beirut of West German citizens Rudolf Cordes and Alfred Schmidt.