NEW YORK (AP) _ A subway train made 20 stops during rush hour today, picking up and dropping off scores of passengers, before anyone notified officials there was a dead body on board, police said.

The dead man, believed to be in his 40s, was reported about 45 minutes after the train began its morning run, said Officer Valerie St. Rose, a police spokeswoman. The train made 20 stops before officials were informed of the body.

Police do not know where the man boarded the train, but believe he was dead for four to five hours, well before the train started out. They speculate that no one noticed him because the train was so crowded and people in too much of a hurry.

``Do you know how many people sleep on the train during morning rush?'' subway rider Mario Licari said. ``Unless the guy slumps into me, I just leave him alone.''

The man was wearing jeans, a polo shirt, black boots and had on him 20 cents, a watch and a comb. No identification was found.

Investigators said the body had no visible signs of a struggle or attack.

The Transit Authority did not return a telephone call seeking comment. The man died on a train that runs from the southern tip of Manhattan to the Bronx.

The body was turned over to the medical examiner to determine the cause of death.