A Howard County day-camp counselor, arrested earlier this week on charges of molesting a 5-year-old boy at the camp, has been charged with sexually assaulting a 9-year-old boy, police said today.

Thomas C. Ayres Jr., 28, of Columbia, arrested Monday for allegedly assaulting a youngster attending a county-run camp in Columbia, was charged yesterday with assaulting another camper on three separate occasions last month, Howard police spokesman Steven E. Keller said.

Ayres, who was being held at the county detention center in Jessup, was charged with three counts of child abuse; three counts of molesting a child under 14 years old; and three counts of assault and battery, Keller said.

Police earlier had charged Ayres with several similar counts of child abuse and assault for allegedly fondling a 5-year-old participant in the county's day-camp program.

Howard District Court Judge R. Russell Sadler today raised Ayres' previous $10,000 bail to $85,000, a court spokesman said.

Keller said Ayres, who is in jail but could not be reached for comment, has not yet been arraigned and has made no pleadings in the case.

In an unrelated development, Howard police yesterday arrested a 34-year-old Columbia man and charged him with committing sexual offenses against four boys aged 8 to 12.

William David Levine was arrested at his home after police investigated reports that Levine allegedly lured neighborhood youngsters into his house and sexually assaulted them, Keller said.