Police in Halifax are investigating an alleged sexual assault against a 16-year-old girl.

Police say the teen was walking through the Dartmouth Common around 10:30 p.m. Saturday when a man approached her.

She told police she became nervous when the man tried to speak with her. Police say she then began to walk faster but the man grabbed her, pushed her to the ground and began touching her in a sexual manner.

Police say the girl screamed and struggled with the suspect, causing him to flee on foot towards Alderney Drive.

The suspect is described as white man between the ages of 25 and 30. He is five-foot-ten, has a medium build and light, buzzed hair. He wore jeans and a white, or light-coloured T-shirt.

Anyone with information about the suspect or the incident is being asked to contact police.