A man who passed himself off as a physiotherapist for 18 months has been fined after the Ministry of Health launched an investigation.

In Auckland District Court yesterday, Jonathon Steven Mann admitted 17 counts of misrepresenting himself as an osteopath and physiotherapist and carrying out treatment on unsuspecting patients around Auckland.

The ministry's investigation found that Mann, a British migrant, was not registered - or qualified to be registered - in either field.

The court fined him $900, but the ministry's chief legal adviser Phil Knipe said it was made clear that size of the fine was decided in consideration of Mann's financial circumstances and didn't reflect the seriousness of his offending.

An expert witness said any unqualified person passing themselves off as otherwise presented "obvious risks to the health and safety of those patients".

Under the Health Practitioners Competence Assurance Act people making false claims of being a health practitioner can be fined up to $10,000, and that can be stretched to $30,000 if they carry out restricted activities.

Mann, whose offending was carried out between January 2007 and July 2008, pleaded guilty to all charges.