The alleged abduction and sexual assault of a Hamilton schoolgirl was a false complaint, police say.

The 15-year-old girl told police she had been forced into a car and raped while walking home from school on Durham St, Nawton on February 27.

Detective sergeant Robbie Hermann of the Waikato CIB said investigators re-interviewed the girl this afternoon.

"As a result of enquiries made into the allegations a number of inconsistencies in the girl's account were identified and when confronted with these the girl admitted to police that she had made up the story and that she had not been raped as she had earlier reported.''

He said the admission was frustrating as it wasted police resources that could be better utilised helping the victims of genuine incidents.

"Many hours work that could have been spent on investigating genuine cases of child abuse have effectively been lost,'' he said.

"In addition to that partner agencies and the girl's school had worked to ensure her needs were being taken care of.''

Hermann said publicly highlighting the incident had inflamed public apprehension and fear.

The girl will be referred to the Hamilton Police Youth Aid Section.

Meanwhile, Hamilton police want to track down a woman who helped save another woman from being raped in the city on Saturday night.

Detective Sergeant Michele Moore of the Hamilton CIB said a 20-year-old woman was walking on Anglesea St when she was dragged off the footpath and into bushes at the Wintec campus on the corner of Collinwood and Anglesea Streets about 11.30pm.

"Her attacker has indecently assaulted the victim as she has struggled and called for help.

"A young woman has heard her screams and come to the rescue of the victim resulting in the offender fleeing the scene on foot. The victim was comforted by the good samaritan before the woman left and the victim has walked to the Hamilton Police Station to report the incident.''

Police want to speak with the woman to help identify the attacker and to commend her for her actions.