Corrupt conduct by former Labor ministers Eddie Obeid and Ian Macdonald in relation to mining licences had cost the state about $90 million, which might never be recouped due falling coal prices.

''So, whether it be seven new schools or 900 teachers as an example, the state has been short-changed,'' NSW Treasurer Mike Baird said.

Illustration: Rocco Fazzari

Mr Baird asked government officials to examine the cost to the state budget after findings by the Independent Commission Against Corruption last month.

ICAC said Mr Macdonald and Mr Obeid engaged in corrupt conduct by conspiring to rig a tender for a coal exploration licence over land owned by the Obeid family at Mount Penny in the state's mid-west.