The Canterbury District Health Board is assuring safety measures were in place when a guest from managed isolation visited a patient at Christchurch Hospital.
Another visitor, who was there on Monday, said they felt the guest, believed to be on day 12 of MIQ, put others at risk, and staff were not happy.
They claim the person was visiting a patient who was not critical or dying.
Canterbury DHB confirmed the visit took place.
Executive lead for Covid-19 Ralph La Salle said robust infection prevention control measures were in place to protect others.
He said those leaving MIQ have a transport plan, wear PPE and are required to return a negative Covid-19 test.
The Ministry of Business, Innovation and Employment said exemptions are very rare.
They can be granted to visit a seriously ill family member at home or in hospital, after 12 days in managed isolation and after two negative tests.