Police have released a composite sketch showing a man believed to be connected to a New Year's Day sexual assault in Newmarket.

The sketch was released Monday, in connection with an assault reported early Friday morning.

York Regional Police said an 18-year-old woman was assaulted at approximately 3 a.m. She was walking westbound on a pathway that runs parallel to Davis Drive, from the GO bus terminal towards Crossland Gate, police said in a statement.

The statement said she was approached by a man who grabbed her, forced her to the ground and sexually assaulted her.

A man interrupted the assault and interacted with the victim, but left the scene before police arrived. Officers are looking to speak to the witness, and anyone else with more information.

They are also looking for a male suspect, described as approximately 5-foot-9 with a lean build. He is estimated to be between 30 and 40, and was wearing a cover over his face.

Police said they do not believe the incident is linked to other sexual assaults that have been reported in the Newmarket area.

Anyone with more information is asked to contact police at 1-866-876-5423, ext. 7071, or call Crime Stoppers anonymously at 1-800-222-8477 (TIPS).