Police investigating sexual violation of 14-year-old girl in Greymouth on the South Island's West Coast

The entrance to the West Coast wilderness trail in the Greymouth suburb of Blaketown. Photo / Google Street View

A 14-year-old girl was sexually violated on a walking track in Greymouth last month, police say.

The January 16 incident was reported to police today and an investigation has begun.

Detective Sergeant Kirsten Norton, of Greymouth, said the girl was attacked about 5pm on the West Coast wilderness trail in the Blaketown area, behind the BMX Park and near the aerodrome.

"She was walking south when she was attacked from behind by an unknown male and sexually violated in an area off the track."

Police want to speak with anyone who may have been in this area around that time, particularly anyone who saw a man behaving suspiciously, Norton said.

"We would also like to talk to people who saw a young woman running in the area between the wilderness trail and New World on that evening. She was not wearing running gear and this may have been noticed as odd."

Police say the teen was sexually violated on the West Coast wilderness trail in Greymouth. Photo / Google Earth

Anyone with information, even what they may consider minor, should contact police on (03) 768 2611.

The teenager and her family are being supported, and police have increased patrols in the area.