A defense lawyer for ex-CIA agent Edwin P. Wilson told a federal jury today that Wilson's alleged business deals with Libya in the late 1970s were a cover for intelligence-gathering carried out at the request of a high CIA official.

Defense attorney Herald Price Fahringer said evidence to be introduced will show that an unidentified agency official approached Wilson shortly after Wilson left the government in 1976.

He was asked to establish a "proprietary," or business front, in Libya to mask espionage efforts on Soviet T72 tanks, MiG fighters and sophisticated ocean mines supplied to Libya.

"What Wilson did was both authorized and legal," Fahringer contended.

It was the strongest, most specific claim that Wilson was operating with CIA approval since his arrest last June on charges of running arms and selling explosives to the regime of Col. Muammar Qaddafi.

The CIA has denied that the onetime career spy had agency approval for his activities, which U.S. prosecutors charge brought millions in profits to Wilson, 54.

Similar claims by Wilson that his deals had CIA blessing failed to convince a federal jury in Alexandria, Va., two months ago.

That jury convicted him of illegally smuggling four handguns and an M16 rifle from Virginia to Libya. Wilson was sentenced to 15 years in prison and ordered to pay a $200,000 fine.

U.S. Attorney Daniel Hedges told jurors today that the government will prove that Wilson conspired in 1977 to ship 20 tons of high explosives from here to Libya aboard a chartered cargo jet in violation of U.S. export laws.

The explosives, called C4, were intended for use in Libyan terrorist operations, including exploding lamps, toasters and ashtrays, Hedges alleged.

Hedges made no mention of allegations reported last week that Wilson, while in a jail cell in New York, plotted to assassinate two Washington-based federal prosecutors involved in the case and five witnesses scheduled to testify here.

Wilson allegedly made a $10,000 down payment to an intermediary to arrange the contract killings, according to news reports. The intermediary reportedly was an FBI undercover agent.

Lawyers on both sides have refused to discuss the allegations. But a source familiar with a closed-door, pre-trial hearing here this week said the session, in the chambers of U.S. District Court Judge Ross N. Sterling, was a "dogfight" over whether prosecutors would be allowed to describe the alleged plot to the jury.

Hedges' failure to mention the allegations in his opening argument today apparently indicates the government lost the pre-trial fight. Sterling has ordered all documents pertaining to the alleged plot, and any subpoenas Wilson may have been allowed to issue for CIA officials to support his claims, sealed.

On Monday, Sterling also ordered the trials of two of Wilson's co-defendants, Houston freight shipper Donald R. Thresher and California lawyer Edward J. Bloom, postponed because of publicity over the allegations.

Today's arguments were preceded by four days of jury selection behind closed doors in an unusual arrangement apparently designed to protect classified documents expected to figure in Wilson's defense.

The courtroom is under tight security, with special U.S. marshals accompanying some prosecutors around the clock.

Wilson, who is in custody in a jail here, faces two more trials in Washington later this year.