The federal government's in-house landlord, the General Services Administration, is seeking new customers--private businesses to rent millions of square feet of unused government space.

The GSA is set to announce that for the first time the U.S. will lease vacant space to the private sector in buildings it owns or rents itself, using a national real estate broker to find the tenants.

The new program is estimated to earn about $25 million a year in revenue for the federal government after the broker's fees.

In the past, this space has simply gone unoccupied if no government agency could could use it, a GSA spokesman said.

"This is another of our efforts to improve the efficiency and cost-effectiveness of government through the use of private-sector techniques," said GSA Administrator Gerald P. Carmen.

Carmen has made a personal crusade of frugality in the use of government space. The agency has a goal of reducing the space needs of the federal government by 20 percent over the next five years, and GSA already has worked hard at setting a good example.

Desks at the GSA offices have been pushed together to the point of extreme intimacy to accommodate a consolidation, and the number of phone lines have been reduced.

The agency also is planning a $300 million increase in rents to federal agencies in October, to a total of $2.1 billion. This rise is mandated by law, but because of budget constraints is likely to aid GSA's goal of getting other agencies to reduce their space.

GSA said that currently its vacancies include 5.8 million square feet of office space, 6.3 million square feet of storage space and 1.3 million square feet of special purpose space. This is out of a total of 230 million square feet in 7,800 buildings that GSA maintains.

A spokesman for GSA said that the agency will advertise throughout the country for a real estate broker and will select one. A standard commission will be paid, to come out of money raised from the rents charged so that no budgeted funds or additional personnel are needed for the program.