The Napthine government is embarking on a massive program to sell lucrative land sites as it builds up a war chest ahead of this year's state election.

Treasury figures show that revenue from land sales has skyrocketed under the Coalition, which is getting a windfall of about $420 million this year from selling off sites, mostly for private development - a 676 per cent increase since Labor was in power four years ago.

Sell, sell, sell: Assistant Treasurer Gordon Rich-Phillips.

Fairfax Media can also reveal that Assistant Treasurer Gordon Rich-Phillips is conducting a highly guarded audit of surplus land, with every department told to review their holdings so that unused sites can be relinquished to help pay for services and infrastructure.

The government's secrecy is in stark contrast to its election pledge - still unfulfilled - to establish a register of significant publicly owned sites to avoid their secret disposal by government, and to improve the transparency of processes associated with their sale.