Lower Hutt Police are investigating a sexually-motivated assault yesterday afternoon, which has left the victim shaken.

Detective Constable Shaun Broughton of the Lower Hutt CIB says a 29 year old female was grabbed from behind by a male just after 1:20pm, on the Moera side of the Hutt river, under the Ava Railway Station foot bridge, near Richmond Grove, Woburn.

"The offender grabbed the victim from behind, and attempted to pull her backwards. She struggled against the offender and eventually broke free from him. The offender ran away across the Ava Railway Station foot bridge, towards Alicetown."

The offender is described as Polynesian, of solid build, around six foot two inches in height. He was carrying a black or navy backpack, wearing a grey sweatshirt and a black t-shirt.

Shaun Broughton says, "Police want to hear from anyone who was in the vicinity of the Ava Railway Station footbridge between 1.10pm and 1.40pm yesterday afternoon, who may have witnessed the incident or seen anyone suspicious."

Anyone with any information should phone Lower Hutt Police as soon as possible on (04) 560 2600 or phone Crimestoppers on 0800 555 111.