The Calgary Police Service is investigating an alleged sexual assault against a woman in northwest Calgary.

Police say a small, light-coloured vehicle followed the woman as she rode her bike west along Third Avenue N.W.

After following her for several blocks, the man allegedly got out of the vehicle and groped the woman near 22nd Street.

The woman fought back and the man fled.

He is described as possibly of Middle Eastern descent, in his mid-20s, roughly six feet tall with a thin to medium build and brown skin.

Police say he had short, black, curly hair and stubble on his face. He was wearing a light, collared dress shirt, a dark jacket and dark jeans and fled in the small, light-coloured vehicle.

Anyone with information about the incident is asked to contact Calgary police.