A 21-year-old woman turned up to an Auckland medical clinic in a critical condition, sparking a police investigation.

Detective Senior Sergeant Albie Alexander of Counties Manukau Police said the woman turned up to the Manukau Superclinic in a critical condition on Tuesday.

"An investigation has been launched and a number of people are currently assisting Police with their inquiries.

"An address of interest is currently the subject of a scene examination."

Victim Support services have been engaged and they, as well as the investigation team, are working with the woman's family.

Inquiries are ongoing and no other information was yet available.