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.

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.

Among the lucrative sites are numerous vacant schools. The most valuable is the former Brandon Park Secondary College, which is expected to fetch about $25 million after tenders close on May 7.

Other schools that have been rezoned for residential development include Oakleigh South Primary, Clayton Primary, Clayton West Primary, Monash Special Development School, Doveton

Secondary College, Doveton North Primary School, Bendigo South East Secondary College and Eumemmerring Primary School.

The Assistant Treasurer's office declined to tell Fairfax Media what land has been primed for sale in other departments - describing the process as ''ongoing'' - but a spokesman insisted the audit would provide taxpayers with better value and would also exclude national parks and state forests.

''The money received from any sale of surplus land is reinvested back into vital services and infrastructure, such as hospitals, roads and schools,'' he said.

Tender documents also reveal that in the past year, about a dozen contracts have been awarded through Treasury for land sales in areas including Heidelberg, Reservoir, Mildura, and Maffra, worth between $370,000 and $10 million.

Government developer Places Victoria is currently selling hundreds of hectares of land to private developers - including 645 hectares of undeveloped land at Epping, Officer and Craigieburn.

And as reported by Fairfax Media earlier this year, the biggest state government land sale in a decade - a 125-hectare new housing development site at Werribee - sold within a week for just over $100 million.

The push to divest more land comes as the government prepares to unveil its election-year budget in nine days, with the Coalition under pressure to pay for an ever-growing list of expensive projects such as the East West Link, a rail link to Melbourne airport, and free tram travel in the CBD.

But revenue from vacant land is soaring, with budget papers showing that sale of non-financial assets - which includes land, buildings, property, plant and equipment - will add $500 million to state coffers by 2015, compared to $54.1 million in 2009-10.

Opposition treasury spokesman Tim Pallas said community needs were being ignored ''as Denis Napthine scrambles to [hold] a fire sale of valuable community resources without the slightest effort to ask the community affected by these sales what they want to occur''.

Property Council state executive director Jennifer Cunich said she supported the government ''getting proactive with its land holdings'' but added: ''All revenues from the sale or redevelopment of government land must be reinvested into addressing the ever-growing infrastructure backlog in Victoria.''

The Coalition went to the state election promising to establish a state register of significant public land, to stop future governments selling it off ''in secret'' - partly to avoid what it described as ''the scandalous backdoor processes'' involved in the sale of Kew Cottages. It also committed to setting up ''an open and public process where the relevant minister must set out before Parliament the reason for the sale of the land before its disposal''.

Both promises have not yet been met, but the government insists the current audit of surplus land will help it establish a new register ''in due course''.

Meanwhile, government rail business VicTrack - which owns of most Victoria's railway land - sold 16 sites last financial year for $7.28 million and this financial year has sold seven sites for $6 million.