Police have apologised to a sexual assault victim whose confidential file was left on a police car dashboard in an Auckland supermarket carpark.

In clear view were details of the assault, including the name, address and age of the victim.

Auckland City District Commander, Superintendent Karyn Malthus told Mike Hosking an investigation is underway.

"We've obviously met with the victim in this case to advise her of that and work with her and make her feel supported," Malthus said.

LISTEN TO THE FULL INTERVIEW WITH MIKE HOSKING ABOVE