Waitemata Police are seeking information from the public after a sexually motivated attack on a teenage girl on the North Shore in Auckland.

The 15-year-old girl was walking home from school through the Awaruku Bush Reserve in Torbay yesterday afternoon at around quarter to four, when a man approached her from behind and indecently assaulted her.

She managed to get away from the offender, who then fled the scene.

Witnesses saw a man moments later on Awaruku Road riding away on a black mountain bike, at speed.

Police have yet to confirm whether this is the same person, but the descriptions provided by witnesses and the victim are similar.

The offender is described as Caucasian, aged in his 40s, and of strong build.

He has black and grey hair and was wearing knee length shorts, a grey shirt with horizontal blue stripes, and black skate shoes.

The victim recognised the man as she had seen him in the reserve three days earlier.