A former youth football coach at a Catholic school in Silver Spring was indicted yesterday on child-abuse charges involving two teenage boys over a two-year period.

John S. Mackintosh, 50, of the 400 block of Old Line Avenue, was indicted by a Montgomery County grand jury on two counts of child abuse stemming from alleged sexual incidents that occurred between Jan. 1, 1980, and Dec. 31, 1982. The incidents allegedly occurred in a weight-lifting room, at Mackintosh's apartment and on weekend outings to the beach and to western Maryland.

Mackintosh is accused of fondling two boys, then aged 13 and 15, while he was coaching at St. Camillus School in Silver Spring. Court documents allege the sexual incidents occurred at least once a week.

Mackintosh, a coach at Pallotti High School in Laurel, could not be reached for comment yesterday. His attorney, William J. Rowan III, said his client will plead not guilty to the charges. Rowan would not say if Mackintosh is still with the school. Richard Damais, principal of Pallotti High School, could not be reached for comment yesterday.

According to court documents, the allegations surfaced in June when one of the alleged victims, now 23, told police about the alleged sexual abuses. A few days later, the second man was interviewed by police investigators, court records show.

Yesterday, Detective Gary Costello, of the county police department's Youth Division, said an investigation is continuing in the case.

Court documents said both men allege Mackintosh fondled them in the weight-lifting room in the basement of St. Camillus Church off New Hampshire Avenue. The men also told police Mackintosh had sexually abused them on "numerous occasions" when they stayed overnight at the coach's apartment on Beacon Road in Silver Spring, court records said.

According to the statement of charges, Mackintosh took nude photographs of one of the boys. Court documents also allege Mackintosh showed the two boys pornographic magazines at his apartment.

If found guilty, Mackintosh would face up to 15 years in prison on each child-abuse charge, a law enforcement official said.