A review into Prime Minister John Key's habit of deleting text messages has found he was unlikely to be breaking the law by doing so.
But because of a lack of advice about his obligations it was possible some public records may not have been handled properly.
"It is possible that some public records may not have been managed in accordance with the requirements of the act," Chief Archivist Marilyn Little said.
Green Party MP James Shaw complained about a possible breach of the Public Records Act in November after Mr Key said he doesn't keep texts following disclosures around his correspondence with blogger Cameron Slater.
Ms Little said a review found recordkeeping advice for all ministers needed to be improved and Mr Key was not advised of his full responsibilities under the act.
"The Prime Minister's current recordkeeping practice for text messages can be viewed as pragmatic, and is likely to comply with the act. There is no evidence of wilful or negligent disposal of records without authority. The act does not require that all public records are retained," she said.
But the review spelled out that text messages were covered under the act and ministers are considered public officers.
"The records, including text messages, that ministers create and receive when operating in their official capacities are public records and should be managed as such," Ms Little said.
She said if a message was received or created by a minister in their official capacity and required action or had some long-term value and needed to be retained then its content should be transferred to staff to manage.
The review did not attempt to recover any of Mr Key's text messages. It said the examination of individual texts would not lead to the improvement of public recordkeeping.
Mr Key said he routinely deleted texts for security purposes.
"It is not my practice to conduct substantive ministerial business by text message," he said in a letter to Ms Little.
At the time of the row, Mr Shaw, now Greens co-leader, said Mr Key would not have to delete text messages unless he has something to hide.