A $4.5 billion deficit was disclosed in an audit of NSW's public finances. This after the coalition government carried out an evaluation of the budget after its triumph in the state election on March 26.

An audit prepared by acting Treasury Secretary Michael showed that the amount of the deficit has increased to $5.2 billion. Lambert's audit is due to be released today.

The added $700 million boost is believed to be caused by the Solar Bonus Scheme that pays householders for feeding solar energy back into the network.

According to News Ltd, the Labor Department sought to "hide" the total loss by leading the state Treasury to produce hundreds of millions of dollars from rail grants.

NSW Premier Barry O'Farrell said, "The black hole that Labor has left ... has now blown out to around $5.2 billion. And I fear it could grow even more as we continue to assess other financial issues."