Ottawa police say there has been an eighth reported sexual assault — this time near the Lincoln Fields Transitway — where a man has attempted to pull a woman's pants down.

Police said the incident happened at noon on Monday on a pathway leading away from the Transitway.

Ottawa police released a composite sketch of a man believed to be responsible for several recent sexual assaults across the city. (Supplied image)

An 18-year-old woman was walking on the path when a man approached her from behind and attempted to pull her pants down. The woman turned around, threw her coffee in his face, and the suspect walked away, police said.

The suspect is described as a white male, 20 years old, five-foot-six with short dark hair with a goatee and wearing a black baseball cap, black sweater and jeans.

Police, who have fielded about 100 tips in recent weeks, had earlier released a composite sketch of a man with a similar description they believed was involved in eight incidents where a woman's pants were pulled down from behind, and a ninth incident where a man followed a daycare worker into a south Ottawa school.

Anyone with information is asked to contact Ottawa police at 613-236-1222, ext. 5760 or Crime Stoppers at 613-233-8477.