A $240,000 review of public prosecutions in New Zealand will look at how to streamline costs without compromising the quality of the service.

One possibility would be to combine police, public agency and Crown prosecutors into one public prosecution service, an idea originally floated by a Law Commission report in 1997 but rejected because the police prosecution service was set up.

Attorney-General Christopher Finlayson announced the review yesterday. It comes at a time of sweeping reforms in the justice sector, from the criminal justice to legal aid to the Family Court to victims' rights.

"The review will be comprehensive, examining the organisational structures, governance, and accountability of agencies within the prosecution system, as well as their roles, functions, and processes," Mr Finlayson said.

"Cost pressures have been building in recent years in the wider justice sector because of increasing case volumes, and we need to ensure funding for prosecution services is sustainable."

Crown Law and police spend about $75 million a year on prosecutions. The cost of prosecutions brought by other state agencies is not known.

The number of cases has increased through the years, partly through a rise in the number of jury trials.

It is hoped that tighter rules now before Parliament on when defendants can choose jury trials will help to curb costs.

The review will be headed by John Spencer, chairman of KiwiRail, Tainui Holdings and WEL Networks, a director of Tower New Zealand and Dairy New Zealand and a deputy chairman of the Legal Services Agency.

It will cost about $240,000, funded through existing baselines of police, Crown Law and the Justice Ministry. Its report is expected to be presented in September.

The last report on prosecutions by the Law Commission in 1997 found, among other things:

Insufficient separation of functions and inconsistent decisions and policies within agencies or areas.

Consultation with Crown solicitors by police and government agencies varied in different districts.

Crown solicitors were involved in cases too late, restricting their ability to influence the initiation of proceedings and the choice of procedures or charges.

The review, which will involve several state agencies, will consider whether these criticisms are still valid.