The federal government is threatening to take away one of the largest public parking lots in the increasingly congested Old Town area of Alexandria unless the city can come up with almost $1 million dollars before Aug. 5.

"If we lost those spaces, it would really hurt downtown business," said Deputy City Manager Clifford H. Rusch referring to a 130-space lot at 219 N. Lee St., which contains 18 percent of the off-street parking in the area. "It would be a real crunch, a terrible jolt," he said.

The federal government, which owns the land, unexpectedly told Alexandria officials two weeks ago that it will dispose of the 1.2-acre parcel unless the city can produce $925,000 to buy it by Aug. 5.

City officials said they were especially vexed for two reasons: They had been trying without success since November to learn the asking price for the land, and the City Council, which would have to approve the purchase funds is in recess until Sept. 11, five weeks after the deadline.

Carlton Brooks, an official of the General Services Administration, which holds title to the land, said the agency has no prospective buyer in mind. "We want the city to have the land. It's just taken us a while to get an appraisal of its value and tell the city about it," he said.

The council could hold a special meeting before the Aug. 5 deadline, or GSA could move the deadline back, according to officials on both sides. Brooks said a change in the deadline is "not acceptable" to GSA.

The city GSA signed a contract in 1969 enabling the city to use the land rent-free as a parking lot in exchange for providing 50 spaces for U.S. owned cars at the City Hall garage nearby, according to a city official.

Last year, the city failed in an effort to have the land declared an historic site by the Interior Department in exchange for an agreement to spend the parking receipts -- about $38,000 a year -- on historic preservation projects elsewhere in the city. Such designation would have enabled the federal government to donate the land to the city.