Director of Public Prosecutions (DPP) in NSW Nicholas Cowdery told the Associated Press that an urgent injection of funds was needed and that his office had already accrued a $3 million deficit only two months into the financial year - which was affecting caseloads.

"We assess the urgency of the case and if it can be deferred for a time then it will be and will sit on a shelf until someone can deal with it," he said.

"That means trials will not be ready to proceed when they are listed ..."

Cowdery said his office dealt with more than 17,000 cases a year and warned the caseload was unsustainable - with concerns that confidence among the public, including victims of crime, would diminish.

"If people don't have confidence that if they complain to the police, their case will be properly investigated and prosecuted, well then they might be inclined to take the law into their own hands," he said.

"It is something we have to guard against."

On Monday, NSW Attorney-General John Hatzistergos demanded to know why taxpayers footed a $110,000 bill for 23 prosecutors to attend a confidence in Brisbane, instead of funding being allocated to staffing courts in Armidale and East Maitland. Activities at the conference reportedly included learning to shoot pistols and machine guns.

Cowdery has yet to respond to the Attorney-General's criticisms.