Convicted former CIA agent Edwin P. Wilson, testifying for the first time in federal court, yesterday refused to divulge details of what prosecutors allege is a personal fortune that he made in private business dealings in Libya and elsewhere.

Wilson, sentenced to 15 years in prison and fined $200,000 last November in Alexandria on firearms smuggling charges, gave only his name and date of birth yesterday before invoking the Fifth Amendment and refusing to answer further questions.

Asked by U.S. District Judge Richard L. Williams for the ZIP code of a 2,300-acre estate owned by Wilson in Upperville, Va., Wilson said he couldn't remember it. "It's been so long, I'm sorry," Wilson said, smiling. "I'll think of it in a second. It's been a lot of years."

Prosecutors are trying to force Wilson, 54, to pay his fine, despite a pending defense appeal of the Alexandria conviction. Assistant U.S. Attorney Theodore S. Greenberg said yesterday that the government fears Wilson's assets are being "dissipated" by legal fees and other financial transactions while the former spy is in prison.

Greenberg said Wilson recently transferred 86,000 pounds, or about $130,000, from a British bank account to pay his defense lawyers. Wilson also is in default on several loans and had bills due in January totaling more than $130,000, Greenberg said.

Williams gave Wilson 30 days to pay the fine, secure a $200,000 bond as collateral or furnish a net worth statement to the government showing he can pay the fine in the future.

Prosecutors' estimates of Wilson's wealth have ranged from $14 million to $20 million. A financial statement carried by Wilson at the time of his capture by federal agents last summer listed assets, mainly real estate, of about $14 million.

The government said Wilson tore up the statement as he was being flown from the Dominican Republic to Kennedy Airport in New York last June. A U.S. marshal retrieved the pieces from an air sickness bag, according to court documents submitted by prosecutors.

Other court papers filed by prosecutors in Houston, where Wilson was convicted 10 days ago on explosives smuggling charges, said the government has evidence that Wilson's net worth in 1982 "approached $20 million. Most of this wealth came from his illegal transactions with the Libyans."

Wilson is expected to be sentenced on Friday in Houston, where he faces up to 25 years in prison for smuggling 20 tons of high explosives to Libya in 1977. A third trial, on murder conspiracy charges, is scheduled later this month in the District.

Defense lawyer John Savarese told Williams yesterday that Wilson's concerns about possible self-incrimination are linked to a federal tax investigation and to an investigation in New York of allegations that he tried to hire a hit man last fall to kill two federal prosecutors and seven potential witnesses. A federal grand jury in New York is expected to indict Wilson soon in connection with the alleged assassination plot, according to a source close to the investigation. The government, which taped telephone conversations in which Wilson allegedly discussed the plot from a New York jail, has said Wilson offered to pay about $850,000 for the killings.

"Mr. Wilson readily moves money from one place to another on so much as a phone call," Greenberg said. "He will use his assets at a moment's notice."