Police are looking for a man they say sexually assaulted a teenage boy on a Manhattan subway platform Sunday.

According to police, the teen was riding a downtown “D” train at about noon when he noticed a man standing over him, touching his groin area. The teen told police the man forced him off the train at West 59th Street, where they boarded a downtown “E” train.

The pair then got off the train at West 50th Street where, according to police, the man forced the teen to perform a sex act at the end of the downtown platform. The man then took the teen’s backpack and boarded an arriving “E” train. The victim followed him onto the train, took back his bag and snapped a picture of his attacker on his cellphone before getting off the train.

The suspect is described as in his 30s, six feet tall and approximately 190 pounds, wearing a grey jacket, beige pants and a black knit hat.

Anyone with information is asked to call Crime Stoppers at 1-800-577-TIPS.