An extra $19.7 million is being pumped into Crown prosecutions over the next four years.

Part of Budget 2016, Attorney-General Christopher Finlayson QC says the investment will ensure serious offenders continue to be held to account through New Zealand's high-quality Crown prosecution services.

Crown prosecutions are managed by Crown Law through a network of 17 Crown Solicitors who are responsible for the conduct of prosecutions on behalf of the Crown. Each Crown Solicitor is a partner in a private law firm.

Mr Finlayson says Crown prosecution services form a vital part of New Zealand's justice system.

"Budget 2016 demonstrates the Government's commitment to effective criminal prosecutions and will ensure the sustainability of these high-quality services into the future." he says.

In total the justice sector receives $837 million over the next four years, plus $56 million in 2015/16.