The Independent Police Conduct Authority could struggle to carry out its watchdog function in the long-term if it doesn't get a boost in funding, the Office of the Auditor-General has warned.

In recent advice to Justice Minister Amy Adams, the OAG summarised an audit of the IPCA and noted the police watchdog's financial sustainability continued to be a focus.

"Although we agree with the Authority's view that it remains a going concern, the Authority needs to plan effectively how it will meet increasing demand using the funding available," the letter to Ms Adams from December 21 last year states.

For the year ended June 30 2015, the IPCA had an operating deficit of $8000. Demand for the authority's services has increased in recent years - the number of complaints rose by nearly 15 per cent last year.


"The Authority has enough Crown funding to meet its forecast expenses in 2015/16. In the long term, limited resourcing could affect the Authority's ability to operate effectively in its role and meet its performance objectives," the letter states.

Funding pressure was a topic when the IPCA appeared before a Parliamentary select committee last month.

Warren Young, group manager operations for the authority, told media that the authority had used up its cash reserves, and would now have to operate within its annual appropriation.

There had been cases that the IPCA did not investigate because it did not have the resources, Mr Young said, including complaints of police using excessive force.

"The ones we regard as critical cases and most significant we do always independently investigate," Mr Young said. "We get 2500 complaints a year...ultimately it is important that the police take responsibility for some of those matters as well. And that's why we have a practice of referring a lot of cases back to police with our active oversight."

At the time, Justice Minister Amy Adams said the IPCA was adequately funded, and was able to take on the most serious claims: "Up until now they haven't put in a request for more funding, they may this year, we will work through that if they do".

Today, Green Party justice spokesman David Clendon called for the IPCA to become an Officer of Parliament, meaning its funding would be set by a cross party committee of MPs.

"At the moment, more than 90 per cent of the cases that warrant investigation are being sent back to the Police to investigate themselves. That defeats the purpose of an independent watchdog."