PORTLAND, Ore. (AP) _ A judge has sentenced a man linked to a radical Moslem group to 20 years in prison for the 1983 bombing of a hotel owned by followers of Indian guru Bhagwan Shree Rajneesh.

Stephen P. Paster, 36, of Los Angeles was convicted Oct. 2 of first-degree arson for setting off three homemade bombs in the downtown Hotel Rajneesh on July 29, 1983.

''I can't think of anything worse in an arson context than setting off three bombs in a hotel occupied by human beings,'' Multnomah County Circuit Judge Clifford Olsen said Friday as he sentenced Paster.

Olsen also ordered Paster to spend a year in jail for his failure to appear in court after his initial arrest.

Paster lost several fingers and suffered eye and ear injuries in the first of the three blasts. No one else was hurt.

Deputy District Attorney Charles French said the bombings were motivated by Paster's involvement in a fundamentalist Moslem group called Fuqra, which he said has two or three chapters in the United States.

Paster is under investigation by federal authorities in Seattle in the bombing of two ''Hindu establishments'' there, but no charges have been filed, French said.

A psychiatrist who wrote a presentencing report on Paster testified that the Portland bombings stemmed from Paster's dissatisfaction with his stepfather's neglect of his religious education, which led Paster to convert from Judaism to Islam.

''Religion became a real good way of acting out some of his anger and frustration toward his stepfather,'' said Dr. Anneke Hathaway said.

Paster ''transferred his anger with his stepfather as a failed leader'' to Rajneesh, she added.

Rajneesh, who claims thousands of followers worldwide, is the leader of a commune in central Oregon.

Paster was arrested shortly after the bombings, but fled Oregon in September 1983 after posting $20,000 bail. He was arrested again in June at Englewood, Colo.

During the trial, prosecutors said police found ''a bomb workshop'' and manuals describing the construction of homemade bombs and munitions at Paster's Los Angeles apartment.

Evidence indicated Paster set three pipe bombs in a fourth-floor room of the downtown hotel. French said one of the bombs exploded in Paster's hands, and the other two went off within 20 seconds of each other about 90 minutes later.