A man who tested positive for Covid-19 spent half an hour in North Shore Hospital may have come into contact with up to 20 staff last Thursday, the Waitemata District Health Board says.
The man bypassed the hospital's front-of-house screening processes while staff were assisting another person and hid from security staff before running into a lift.
Director-general of health Dr Ashley Bloomfield says people who try to deliberately avoid security arrangements in hospital are putting staff and patients at risk.
Prime Minister Jacinda Ardern said the person would understand the magnitude of what happened.
Police have been made aware of the incident by health authorities.
"While this a health-led matter, police are currently working with Waitematā DHB to ascertain whether any breaches of the Health Order have occurred," a police spokesman said.
An email this morning to Waitemata DHB staff said that a "small number of colleagues have been temporarily stood down from work after coming into contact with a member of the public who has tested positive for Covid-19".
"These North Shore Hospital-based staff will undergo testing and will be away from work until they are cleared to return. This situation has come about after a man acted evasively to breach our strict alert level 4 hospital visitor rules on 16 September.
"He bypassed front-of-house screening processes while staff were assisting another person and hid from security staff before running into a lift.
"This person has acted deceptively to break the rules everyone else has followed and potentially exposed people to the virus in the process," an email to staff said.