On the outskirts of this historic city on the west bank of the Rappahannock River stands a bustling new shopping mall, a multimillion-dollar monument to Fredericksburg's financial woes.

Four major department stores have left the city, lured away to the mall's lavish quarters near an interstate highway interchange. City officials covetously eye the white brick plaza, complaining that Fredericksburg's sales tax revenues recently dropped nearly 17 percent. They say the mall's opening also threatens the city's real estate taxes.

To recoup its losses, Fredericksburg has turned to a time-worn remedy: a land grab. The city wants to double its size and increase its revenue by annexing six square miles of adjoining Spotsylvania County, including the booming $40 million Spotsylvania Mall.

"The issue, as we all see it, is survival," says Fredericksburg Mayor Lawrence A. Davies. "We don't feel that this is an invasion of alien territory."

Fredericksburg's move, firmly opposed by Spotsylvania, marks an upsurge of city-county conflict in Virginia after a nine-year moratorium on annexations and a 1979 overhaul of the state's annexation laws. Densely populated counties, chiefly in Northern Virginia and the Richmond area, were granted permanent immunity from annexation.

In the past year, annexation disputes have resurfaced around Virginia's smaller cities, faced with fiscal pressures, business flight and lack of open space for development. Smaller cities have taken steps to seize sometimes valuable land from neighboring counties in the Shenandoah Valley, Southside and Tidewater. In Washington's outer suburbs, Manassas recently hinted at a similar move against Prince William County.

What makes the disputes so intense is money. Millions of dollars in tax revenues often are at stake. Under Virginia's unique structure of local governments, the state's 41 cities are separate from its 95 counties. Cities usually must pay counties for any land they annex, to offset the real estate and sales taxes the counties will lose. Fredericksburg is proposing to pay Spotsylvania $4.5 million for its land.

The annexation proceedings themselves ultimately become lawsuits, conducted before a panel of three state judges, and costing the battling governments hundreds of thousands of dollars.

Controversy has long surrounded annexation in Virginia, sometimes heightened by political or racial overtones. In recent decades, a bitter and protracted dispute occurred in Richmond, which was accused of trying to dilute the political power of its black population by annexing part of Chesterfield County. Another celebrated clash pitted Alexandria against Fairfax County.

Historically, annexation gave cities the right to expand with population growth by claiming land from rural counties poorly equipped to provide additional government services or impose new taxes. But with the spread of more heavily developed counties, the issues changed. Continually threatened by loss of land, counties campaigned for stiffer curbs, leading to a state study and the annexation moratorium, lifted only last year.

In Fredericksburg, a city of 15,000 residents about 50 miles south of Washington, the clash clearly centers on the Spotsylvania Mall, an enclosed shopping plaza that opened last year near an I-95 interchange west of the city. It quickly enticed many Fredericksburg shoppers to its 73 stores. Additional shops are expected to open soon.

"That's the gem in the county crown that the city wants to take," says Steven T. Foster, administrator of the rapidly growing, largely rural county. "It would severely set us back."

Fredericksburg has not yet acted to annex the area, but the City Council is considering an annexation measure and city officials openly discuss their plan. The county took the offensive by asking a state annexation commission for immunity from annexation. The commission arranged city-county negotiating sessions, which are expected to continue for some time.

The city has carefully mapped its territorial aims in an attempt to achieve maximum revenue at minimum government expense. The area sought for annexation -- two tracts west and south of the city, currently valued at $87 million -- includes not only the mall, but several other smaller shopping centers, motels and open land for future development. All are potential revenue sources.

City officials regard residents, especially schoolchildren, as a drain on revenue. So Fredericksburg strategists shaped their proposal to avoid a major population increase. An estimated 3,100 residents live in the area the city wants, including only 600 to 1,000 school-age children.

So shrewdly has Fredericksburg gerrymandered its prospective land acquisition that the proposed boundary juts around the home of Spotsylvania Supervisor M.E. Hicks. The bend has been dubbed "Hicks' notch."

For some Fredericksburg officials, the economics of annexation are tied to the politics of regional power. "If we don't do something, we're going to be a Falls Church or a Fairfax City," says Fredericksburg City Attorney Walter J. Sheffield. "It is like a tick on the tail of a dog."

Other city officials see annexation itself as a painful cause of regional strain. "Annexation is a dirty word as far as counties are concerned," says City Councilman Samuel E. Perry, who voted against the move. "Sometimes I think I've got a contagious disease when I go out there."

No referendum has been held, nor is one required. But opposition is clearly widespread in Spotsylvania, where many residents and business owners fear their taxes will rise.

"I blame the legislature to some extent," says Spotsylvania County Attorney Robert W. Ackerman, recently elected to the state House of Delegates. "They allowed counties and cities again to go at each others' throats, to create bitterness."

Others regard annexation as inherently contentious. "A solution to one is anathema to another," says M. H. Wilkinson, executive director of the Virginia Commission on Local Government, created by the 1979 legislation to hear, study and make recommendations in annexation disputes.

With the moratorium lifted, localities quickly renewed long-simmering annexation battles. The first was Harrisonburg, a Shenandoah Valley city about 100 miles southwest of Washington. With businesses departing and land for development scarce, the city sued to annex part of Rockingham County, winning 11 square miles in exchange for $8.5 million.

"It's really not the amount of land that hurts; it's what's located on that land," says William G. O'Brien, administrator of Rockingham County, which has appealed the lower court decision to the Virginia Supreme Court. "The award really strips the county of its commercial base."

In Tidewater, Williamsburg negotiated a tentative agreement earlier this year to annex four square miles of land in James City County. The Southside city of Emporia is seeking to annex land in Greensville County.

In Northern Virginia, Manassas recently negotiated a $4.5 million contract to buy 242 acres of privately owned land in adjoining Prince William. The tract connects the city with its airport, also situated in the county. If the city buys the land, it might then seek to annex the airport and connecting strip, a move that would raise untested issues.

Under the 1979 law, Prince William gained immunity from annexation by cities. It is not immune, however, from annexation initiated by residents or property owners. As a property owner, Manassas might seek to annex its own land.

Says Prince William Board of Supervisors Chairman Kathleen K. Seefeldt, "We do not wish to concede an inch of territory."