A psychiatric nurse's "inappropriate" relationship with a mental health patient has been condemned by a healthcare watchdog after it was discovered he visited the woman in a motel and bought her gifts.

The "much older" registered nurse communicated with the woman, who was in her 20s and had a complex mental health history, outside of work, a Health and Disability Commissioner's investigation found.

In 2020, the nurse took the patient out several times in his car, bought her shoes and food, and visited her in a motel.

Deputy Health and Disability Commissioner Dr Vanessa Caldwell today found the nurse in breach of the Code of Health and Disability Services Consumers' Rights (the Code).

During the investigation, the man denied having a sexual relationship with the woman, or that he ever touched her.

The nurse further said he was "physically incapable" of having a sexual relationship and had been too embarrassed to report the threats to his manager.

He claimed the woman had blackmailed him into meeting her by threatening to make allegations of sexual assault.

The case's full report and which District Health Board (DHB) the man was employed by was not released publicly.

But in a case summary, Caldwell said the nurse's conduct was exploitative and that he had breached professional and ethical boundaries "while having an inappropriate relationship with a patient".

"In my view, the nurse's behaviour towards the woman was self-interested, and did not have regard for her vulnerabilities or the significance of his actions in forming a relationship with her," Caldwell said.

"Under the Code, the woman had the right to be free from discrimination, coercion, harassment, and sexual, financial or other exploitation. She had the right to have services provided that comply with legal, professional, ethical and other relevant standards."

Caldwell recommended that the nurse be referred to the Director of Proceedings to decide whether any action should be taken. She suggested the nurse provide a written apology to the woman.

Although Caldwell did not consider the DHB had breached the Code, she recommended that it implement a system for clinical supervision, including an audit of staff compliance with the system, and report this to the Health and Disability Commissioner.

She also recommended that the DHB conduct an audit of mental health staff to confirm that the expected staff appraisals have been completed.