A person who snuck into a surgery at Wellington Hospital has prompted the Capital & Coast District Health Board to review its security systems.
The health board's chief medical officer John Tait said the member of the public accessed an operating theatre under "false pretences" last week.
A University of Otago medical student was also involved, and they have been banned from the health board's buildings while it investigates the breach.
The person who should not have been in the hospital has been referred to the police.
Tait said the health board has apologised to the patient affected and their family and contacted the Office of the Privacy Commissioner.
In a statement, the University of Otago said it had also launched its own formal investigation into the incident.
It wouldn't confirm how the medical student was involved, but said the person was "currently not able to undertake clinical placements".
"Please be assured that the University of Otago places very clear expectations on its students in hospital settings and has rigorous processes to address any possible breach of those expectations," a spokesperson said.