Northern Territory Police are investigating an assault on a woman that occurred in Gillen last night.

Around 8.30pm the woman was walking her dogs along Memorial Avenue, past Flynn Drive towards the Jim McConville Oval, when an unknown male approached her from behind and assaulted her.

The offender is described as being of Aboriginal appearance, approximately 175 centimetres, medium build, between 20 to 30 years old, short black hair, wearing a red and black flannelette shirt, black shirt underneath and denim jeans.

Anyone with information is urged to contact police on 131 444 or report it anonymously via Crime Stoppers on 1800 333 000 referencing PROMIS number 9526737.