A staff member at a Hamilton medical clinic is being investigated by the Ministry of Health.
The ministry says it is investigating concerns about the qualifications and training of the person at the Family Clinic in Vercoe Road.
It says the person may have breached the Health Practitioners Competence Act by giving vaccinations, taking cervical smears and inserting IUDs from October 2007 without being qualified.
The ministry says the investigation will be able to determine if the staff member acted appropriately.
A confidential phone line has been set up for patients concerned about treatment they received. It is 0800100 178.
The Waikato District Health Board says an audit of enrolment procedures at the clinic has found irregularities, but it is not able to lay criminal charges.
The Family Clinic was audited from the period beginning late 2007.
Waikato DHB planning and funding general manager Brent Paradine says the exact detail of who initiated claims for patients is not known.
Mr Paradine says the investigation will be reopened if it can be proved who wrongfully enrolled the patients.