SAN FRANCISCO (AP) _ A jury was selected Monday in the trial of a man accused of delivering a bomb-laden bouquet to his employer's estranged wife.

The bomb exploded in an federal office last Nov. 17, injuring the woman and a co-worker.

Shaun J. Small, who had been held without bail since his arrest the day after the blast, has pleaded innocent to charges of having an unregistered explosive device and maliciously damaging federal property.

The charges carry penalties of up to 40 years in prison and $750,000 in fines.

U.S. District Judge Frank Kaufman said opening arguments would begin Tuesday, and estimated the 27-year-old defendant's trial could last two weeks.

Witnesses said at the time of the bombing that a bouquet of dried flowers was delivered by a man dressed in a bellhop uniform to the General Services Administration office where Melanie Pilaski, 41, worked.

She was on the telephone when another worker told her there was a package for her on her desk. Investigators said she reached in and pulled out a box nestled in the middle of the flowers and it went off, tossing burning material around the area.

However, investigators said small glass marbles that were supposed to be hurled out at high speeds were not ejected.

Attached to the box was an unsigned card that said, ''Eespecially for you,'' according to investigators.

Mrs. Pilaski and Pamela Castro, 42, suffered cuts and burns.

A man tried to deliver a bouquet later to Mrs. Pilaski's parents, but her father, Willard O. Swanstrom, refused to accept it because he had seen a television news report about his daughter being injured.

Mrs. Pilaski had filed for divorce last Oct. 1, and Small and her husband were under a court order prohibiting contact with her during the bitter proceedings.

Mrs. Pilaski said Small's parents in Florida had helped her husband after he moved from his native West Germany. Small came to California when he was 17 to stay with the Pilaskis and get treatment for an eye problem.

Pilaski told reporters that he thought of Small as his son. Assistant U.S. Attorney Joel Levin has described Small as an ''immature, vindictive'' man who was ''willing to do anything to serve his master,'' Pilaski.

In the divorce filing, Mrs. Pilaski demanded a half-share of a $3 million property she said she jointly owned with her husband.