For months, discovery of one of the most important U.S. postage errors -- a 100-stamp sheet of $1 stamps with a candlestick printed upside down -- has been credited to workers at an anonymous "business" in northern Virginia.

Actually, the misprints were found by nine Central Intelligence Agency employes who took 95 of them from CIA supplies and sold 86 to a New Jersey dealer, apparently for thousands of dollars, according to the dealer and a government report made available yesterday.

The CIA is investigating the nine for using their government positions for profit, said Bill Bergstrom, office manager of Jacques C. Shiff Jr. Inc., the stamp firm in Ridgefield Park, N.J., that obtained the inverted stamps from the workers.

CIA spokeswoman Sharon Foster confirmed the investigation but declined to provide details.

"We don't take questions of improprieties lightly," she said. " . . . We have very high standards here."

Linn's Stamp News, which reported the CIA link in editions due to reach readers this week, said a CIA employe bought 95 of the so-called "candlestick inverts" for the agency at a McLean post office March 27, 1986. The whereabouts of the other five, presumably sold to the public, are unknown.

The CIA workers apparently sold 86 stamps to the dealer, including one that was torn, and kept the other nine, according to Charles Yeager, Linn's Washington correspondent.

Only three of the 86 are reported to have been sold, including one for $17,600, Bergstrom said. One has been donated to the Smithsonian Institution by a dealer.

Bergstrom and Yeager said the misprints' ultimate value could be as high as $115,000 each.

A similar value was placed on another famous U.S. stamp error, the 24-cent air-mail stamp of 1918 depicting an airplane upside down. Only 100 of these are known to exist.

Yeager, a stamp-production specialist, said the candlestick stamps could be more valuable than the 1918 misprint. If his assessment is correct, the 95 misprints are worth more than $10 million.

The misprinted sheet was among 28.2 million candlestick stamps printed by the Bureau of Engraving and Printing. Such stamps are printed in sheets of 400, then divided into four 100- stamp sheets before being packaged for distribu- tion.

What happened to the other 300 stamps on the misprinted sheet is not known.

After the CIA employe returned from the post office, her supervisor noticed that the orange glow and flame on the stamps was upside down, according to an investigator's report released by the Bureau of Engraving and Printing in response to a Freedom of Information Act request.

The employe consulted with other workers, one of whom was a stamp collector, and they took the stamps to an unidentified stamp dealer in Annandale, who bid on them and suggested that Shiff, a major stamp auctioneer, would probably make a better offer, the report said.

Six days after the discovery, the group sold 86 stamps to Shiff, who announced the find and, on May 28, 1986, sold the first inverted one for $5,500.

The employes' names were deleted from the bureau's report at the CIA's request. The report was first released this summer to a stamp dealer who had secured some of the misprints from Shiff for sale and expressed concern about their validity.

"The dealers wanted to establish that the stamps didn't come out of the back door at the bureau . . . that these stamps weren't illegal," Bergstrom said.

Collectors and government printers generally question whether a misprint may have been created deliberately by a printer hoping to reap a financial windfall.

The bureau investigation, according to the papers released yesterday, confirmed that the candlestick inverts were created inadvertently when one sheet of 400 stamps became turned upside down between two printing presses.

Bureau employes reported finding no errors in preshipping checks of the candlestick stamp, and the report assumed that clerks at the McLean postal substation at 1544 Spring Hill Rd. sold five of the stamps to the public before the CIA purchase.

Bureau investigators apparently did not know that the CIA workers kept nine of the stamps. One of them surfaced this summer at a stamp shop in Arlington, where it was offered for sale at $17,000.

That led to Yeager's discovery in July that 95 were known to exist. One, however, was badly torn, apparently by the CIA workers, making it worthless.

Silas A. Oglesby, a bureau agent who interviewed some of the CIA employes, said in his report that one "emphasized that the 86 postage stamps, of a normal face value of $86, were not stolen from . . . {the} agency in that the 86 inverted stamps were replaced with regular stamps."

Bergstorm said that bureau agents made no effort to force the company to surrender the stamps, and that he expects that the CIA will force the workers to give the government profits from the sale.

He would describe them only as being in the "low five figures."

"But we'll never know" what happens to the workers, he said, citing CIA privacy rules. Foster agreed, saying the agency never discusses internal disciplinary procedures.