Two drunk adults fastened their seatbelts but left two children unrestrained in the back seat of a car as they drove home swerving across the highway, police say.

Worried motorists phoned police about the car when it was spotted swerving in its lane heading north on State Highway 1 at Horotiu on Friday.

The 29-year-old female driver was already wanted by police because her learner licence was suspended for a lack of demerit points.

She recorded a breath alcohol reading of 1007 milligrams but officers were more appalled to find two children, aged 3 and 5, sitting unrestrained on the back seat.


"A man sitting in the front passenger seat had also been drinking but he also had the presence of mind to have a seatbelt on," Sergeant Juliet Burgess said.

"As a police officer I have to ask where people's minds are at when they can drink heavily but still have the presence of mind to put their seatbelts on but give no thought to the risks posed to the children in the back left unrestrained while being driven by a drunk driver."

Ms Burgess, the officer in charge of the Huntly strategic traffic unit, said the motorist who reported the swerving car to police had "prevented a potential tragedy".

A woman would be charged with drink-driving as a result of the incident.

It is the latest in a string of incidences that have north Waikato police concerned by the number of women drink-driving.

Nine drivers were found over the legal alcohol limit in Huntly and Ngaruawahia on Friday and Saturday. Seven of them were women.

The highest reading was that of a 32-year-old Ngaruawahia student whose car hit with a parked trailer.

She drove off and was found by police at house. She was tested and returned a breath alcohol reading of 1108 milligrams.