Litton Industries' Amecom division yesterday announced a $10 million expansion of its Prince George's County facilities that will increase its work force by 700 employes.

The expansion will be the biggest single private-sector, jobs-producing project ever for the county, Prince George's economic development officials said.

Litton Amecom has more than 1,500 people at its College Park complex, making it the largest private employer in the county.

Maryland Gov. Harry Hughes and Amecom President Charles Fink announced the company's plans at a press conference in Annapolis.

State economic development officials estimate that the 700 jobs will add $12 million to $14 million to Amecom's annual payroll of $43 million. County officials said it is too early to project what tax revenues will be realized.

Amecom, which was acquired by Litton in 1957, develops and manufactures high-technology communications systems and defense electronics components. It is part of Litton Industries' $1 billion advance electronic systems group.

Amecom will begin construction this spring of a 129,000-square-foot building to expand its 340,000 square-foot research and manufacturing facility on Calvert Road.

Litton Amecom will occupy 51 acres in a campus-like setting after acquiring a 35-acre site for which it paid the University of Maryland about $2 million. The property includes 26 acres in Riverdale and nine acres in College Park. The deal also calls for Amecom to pay the university $400,000 for a couple of small buildings that will be demolished or removed from the property.

In addition to what the 700 jobs will mean to the economy, the larger impact is that the county was successful in retaining "an extraordinarily desirable company" that had been courted by several local jurisdictions, County Executive Parris Glendening said yesterday.

Glendening cited the importance of the Amecom decision in a review of the county's overall economic development program at a breakfast meeting of the Prince George's County Chamber of Commerce.

In a brief interview before leaving to join the governor in Annapolis, Glendening said he was pleased with the outcome of an "extraordinarily complex deal" that involved state, county and university officials.

Early in the negotiations, the principals had discussed the feasibility of a land swap between Amecom and the University of Maryland.

Amecom subsequently agreed to pay $50,000 an acre for the land adjacent to its existing facility. A Litton official said the money was paid to the state, which will apply it to the university's capital budget.

A spokesman for Hughes said the state became a prime factor in the ultimate agreement because "the major stumbling block was the funds transfer, which we had to approve."

Fink said Amecom elected to remain in Prince George's because of the company's proximity to Washington and the federal government.

Moving to another area would be difficult, he added. A company runs the risk of losing a large part of its work force when it relocates to another area, Fink said.

Amecom's decision will be a major selling point in the county's business attraction program, said Gordon Hubley, marketing representative for Prince George's County's Department of Economic Development.

"I think it's significant in that it means a major high-tech firm with a worldwide reputation is staying in the county," Hubley said.

Litton Amecom's designs, tests and manufactures defense electronics, radio communications, telecommunications, graphic communications and air traffic control systems. Its primary customers include the Defense Department, the Federal Aviation Administration and prime govvernment contractors.