Police say they have moved to put a more robust system in place after serious failures in their investigation of child abuse cases during the last decade were identified in an Independent Police Conduct Authority (IPCA) inquiry.

IPCA chairwoman Justice Lowell Goddard released the second part of a nationwide inquiry yesterday into how police conducted child abuse investigations, with police slated for undesirable practices, particularly in the Wairarapa region.

Several officers have faced code of conduct investigations as a result of two major police operations which delved into child abuse files, with the results of some conduct cases still pending.

Police Commissioner Howard Broad said the examination was a thorough one covering all policies, procedures and practices and conduct as related to child abuse.

"The IPCA found that mostly we did conduct ourselves to the standard expected but in some cases we did not and so we have moved quickly to fix these and to put a more robust system in place."

Police were committed to ensuring a consistently high standard for child abuse investigations and improvements to the police case management system which applied to all investigations were being carried out as a priority, Mr Broad said.

The case management system would help better manage the 400,000 or so files each year.

"While we have extremely committed and dedicated investigators doing their best they were not sufficiently supported by good audit and assurance practices at that time to enable us to keep track of, and manage, those investigations and as a result some were not attended to as they should," Mr Broad said.

Justice Goddard noted that police had responded positively to the first part of her report by setting up a child protection implementation project team and recommended that continue for at least another year to ensure the new practices were well established nationally.

The probes began when a Masterton police officer, Detective Suzanne Mackle, complained of her workload dealing with Wairarapa sexual abuse cases. By June 2006, she held about 142 child abuse files in which there had been little or no progress.

While police chiefs set up practices to rectify the situation, they accepted advice from the officer in charge of the Masterton CIB, Detective Sergeant Mark McHattie, that the situation was being managed. He said on August 31, 2006, the cases requiring action had reduced to 57 files. Five days later, he said it was down to 29 files.

But a police audit carried out in 2008 identified 46 files had been closed during August and September 2006, the majority of them on August 31 and September 31.

The audit found 33 of them were "filed incorrectly" or "inappropriately resolved".

Police undertook a thorough audit of child abuse files nationwide and the results showed that delays and other problems in child abuse investigations were not confined to Wairarapa, although nowhere else was the problem so acute.

The IPCA was advised that police started 18 code of conduct investigations. Five staff were cleared of any misconduct and dealt with through informal processes. Six more investigations had been completed and police were still to complete seven more.

After all investigations were complete, decisions would be made by the police national disciplinary committee, the IPCA said.

Sixty seven other staff were subject to informal interventions as a result of the two police audits.

The IPCA made 34 recommendations in the first stage of its report.

It reviewed more than 41,847 documents, conducted hearings involving 55 examinations on oath, with 33 interviews.