There are further signs of strain in the financial world of Dominic F. Antonelli Jr., the real estate developer, investor and PMI parking magnate who is fighting to stay out of bankruptcy court.

Vienna-based Huntmar Associates Ltd., one of Antonelli's primary real estate development partners, has been laying off employees and more layoffs are expected. The stock of Washington Corp., a public company of which Antonelli is a director and major shareholder, has been trading at depressed prices, and the company recently disclosed that it has missed payments on bank loans.

And the man who began his career as a parking lot attendant, and amassed what was considered to be one of the largest fortunes in Washington, recently put his 22-acre Potomac estate up for sale for about $12.8 million.

The Potomac residence, which symbolized Antonelli's success and comfort, includes a seven-bedroom house, staff quarters, lighted tennis and croquet courts, a swimming pool, a gazebo, a pond and stables for nine horses.

The listing has attracted attention among Washington area real estate executives and brokers, who have viewed it as a sign of Antonelli's financial distress. However, one source close to the 68-year-old Antonelli said the decision to put the house up for sale was driven by other considerations.

Antonelli's problems stem from a variety of risky real estate investments that he undertook in the late 1980s. At a stage in life when other businessmen might have been content to rest on their laurels, he forged partnerships with other developers and guaranteed loans on their projects.

Now, many of those projects are in trouble, and Antonelli is hard-pressed to make good on his guarantees. His attorney, Roger Frankel, declined to comment yesterday. Frankel recently disclosed that Antonelli could be forced to seek bankruptcy court protection if his lenders don't give him time and flexibility to reorganize his borrowings.

Huntmar Associates, which has undertaken numerous projects in partnership with Antonelli, has laid off at least half of its staff of 50 people since the end of last year, sources said, and employees there were expecting additional layoffs this month. Huntmar President Hal Boles said the company is still assessing its staff requirements.

The company has been trying to renegotiate loans with lenders, including Chase Manhattan Bank. "We are in serious negotiations with the banks on a variety of things, as all developers are," Boles said yesterday.

Meanwhile, a contractor has filed a court complaint against one Huntmar partnership seeking to put the partnership into involuntary bankruptcy. Boles said there were "no grounds whatsoever" for the contractor's complaint.

Huntmar's projects include office and industrial developments in Herndon and Loudoun County. The Huntmar president said Antonelli "is a partner in everything I do."

Adding to Antonelli's problems, the Washington Corp., a publicly traded real estate company based in Chevy Chase, reported on July 30 that it needed "a general renegotiation" of its debts. According to available SEC filings, Antonelli's holdings in the company, which were worth more than $1.4 million earlier this year, have since lost about $1 million in value as the companies finances deteriorated.

Washington Corp. Chairman William N. Demas wrote that the company "has not made interest payments due on certain of its secured loans from commercial banks and is in discussions regarding the revised terms of these loans." The company saw purchasers walk away from two contracts to buy land from the company this year, and a third deal was delayed until late next year, Demas said.