A Mongrel Mob member says he knows the identity of the police officer who left a confidential document at a Lower Hutt house during a raid last year.

An Independent Police Conduct Authority (IPCA) report into the incident found police failures amounted to misconduct and a breach of confidentiality, but the person responsible had not been identified.

The authority launched an investigation after the document was left on a table at Anthony Pairama's house during a raid on February 11.

Marked "restricted", the document contained details on the eviction of 10 members of Mr Pairama's family from five state houses in Farmer Cres, Pomare,

Mr Pairama told Radio New Zealand the police officer who left the document at his house was careless and obnoxious, and did not show him a search warrant until long after she had entered his house.

He said he was certain of the officer's identity, but the IPCA had not asked for input in its inquiry.

The IPCA said it was undesirable that nobody had confessed to leaving the document at the house.

Police investigated the incident and interviewed two officers, but were unable to identify the person responsible.

The IPCA said it agreed with the police decision to address the matter through training, "as no particular officer has admitted responsibility or been identified as responsible".

It recommended police introduce instructions on the handling and disposal of operation orders.

The document contained details of the woman whose original complaint of intimidation had sparked the police investigation.

It also detailed the names and responsibilities of 50 officers working on the case, a risk assessment of the street, details of how raids would be carried out and the radio call signs police used to identify themselves.