More than 700 allegations of police misconduct have been made this year, the majority being claims of investigation failures, unprofessional behaviour, and excessive use of force.

However, statistics also show several serious accusations against off-duty cops, including 2 for sexual misconduct and 10 for violence.

According to the police professional conduct statistics for the first 3 months of 2017, there were 557 reported "incidents" across New Zealand, which involved 637 police staff, resulting in 725 allegations of various forms of misconduct.

The top five allegations by category were service failure (251), unprofessional behaviour (127), breach of official conduct (90), use of force on-duty (77), and arrest/custodial malpractice (54).

A service failure allegation is defined as police conduct during criminal investigations, victim support, and court proceedings.

Of all the allegations levelled at police this year, just 24 were upheld. There have been 153 completed investigations into the accusations.

Not included in the statistics is the Invercargill Anzac Day shooting of Verity Ann McLean, who was allegedly murdered by her husband and off-duty police officer, Ben McLean.

McLean has also been charged with the attempted murder of Garry Duggan.

Investigations into allegations of sexual misconduct against 2 off-duty officers are also yet to be completed.

A senior Northland police officer is currently under criminal investigation, and a separate inquiry by the Independent Police Conduct Authority.

There were 25 allegations of police harassment, bullying and discrimination against the public, with one complaint being upheld.

Eight allegations of internal police bullying were also made, none of which have had their investigations completed.

Six allegations of an unauthorised use of a database were reported, with the two completed investigations into the offences being upheld. A further 2 allegations of misuse of email or internet were still under investigation.

Former police officer Jeremy Malifa, 34, was charged in January with 21 counts of unauthorised access of the Police National Intelligence Application computer system.

Malifa, who is understood to have used the system to search for several women's personal information, entered guilty pleas to all the charges earlier this month.

Twenty five allegations of a breach of privacy and confidentiality were recorded, with two complaints upheld, and 3 corruption claims made, all of which are still under investigation.

Professional conduct national manager Superintendent Anna Jackson said it was an "encouraging sign" to see the number of incidents trend down, however, she emphasised police were "never complacent" about an allegation.

The total number of allegations is projected to be about 2220 this year, compared to 2690 last year, and 2759 in 2015. The total of upheld allegations is also trending down.

"There is a robust process in place to manage complaints about staff conduct and we are not afraid to investigate and hold our people to account where appropriate," she said.

"But although there has been a decline in upheld matters, there are still a number of ongoing investigations to be completed," she added.

She said allegations of excessive force and unprofessional police behaviour were a concern, with new tactical communications training helping cops de-escalate situations.

"But it's a reality of policing that force will need to be used on occasion in order to keep the public, our staff or even the subject themselves safe.

"Ultimately, it's the person's behaviour, and the risk they pose to themselves or others that determines how we respond, regardless of their age, gender or any other criteria."

The allegations come from the nearly 1 million jobs police attend throughout the country every year.

Of the use of force allegations by police, 52 were allegations of excessive manual force, 8 for a police dog bite, 6 for restraints (handcuffs), 5 for a Taser, and 5 for OC spray.

Fifty four allegations of improper arrests and custodial procedures were also made, 3 of which have been upheld.

In January, a man was left in a holding cell at Masterton District Court for 48 hours over a weekend by police with no food or bedding.

He was finally discovered when staff returned to the courthouse on the Monday morning, forcing a police apology.

A week after the incident, the Herald also revealed a 14-year-old girl was left in a locked interview room at a Wellington police station for more than six hours.