A search engine designed to find all government property is launched today to help the public suggest surplus buildings and land that could be sold off.
Francis Maude, the Cabinet Office minister, said the easy-to-use tool was a key part of the coalition's drive to "increase transparency, save money and support regeneration and growth".
The "right to contest" - allowing people to force the government to justify its use of land or property, both vacant and occupied, or release it - was announced at the start of this year. The move extended a right that already existed for local authority land and property, where applications go before the department for Communities and Local Government (CLG).
However, the Cabinet Office made no mention of a future search engine for local council property, to help the public - suggesting that was a matter for the Local Government Association.
Maude said: "As part of our long-term plan for a stronger economy we are slashing our own costs and getting the most out the property we own. Since 2010, we have got out of 1,250 properties, but we need to do more.
"We want the public to use this new map and the right to contest to challenge us to release properties we are not using efficiently enough to cut the deficit, support growth and provide more houses."
The property finder map reveals that the government owns 18 sites in Edinburgh and 17 in Cardiff, but, unsurprisingly, many more in London (61).
However, Maude made clear that "historic assets such as Downing Street or the Treasury building" - part of the government's £330 billion property empire - will not be sold off.
Under the scheme, applicants must complete a short form giving details of the site and their reasons for it being released.
The Cabinet Office said cases are rejected only if departments can demonstrate that the site is vital for operational purposes, or that alternative plans offer a better economic use.
It said the 1,250 buildings vacated since 2010 had cut the cost of running the government estate by £647 million.