A noontime blaze yesterday in a Food and Drug Administration building near Capitol Hill prompted the evacuation of 1,865 government workers and threatened thousands of animals used for scientific experiments there.

FDA officials said the two-alarm fire began in a third-floor laundry room of the government laboratory building at 200 C St. SW. Officials said smoke from the blaze threatened to upset delicate nutritional and genetic experiments that agency scientists conduct on animals there.

Dr. Sanford A. Miller, director of the FDA's center for food safety and applied nutrition, said that "apparently" there was no harm to the 15,000 animals -- including rats, mice, rabbits and Japanese quail -- housed in the building.

D.C. fire officials said it took about 50 minutes after the 12:07 alarm to bring the fire under control. Damages from the fire, smoke and water were estimated at $200,000, and most employes were kept out of the building for three hours.

Within an hour, Miller and other FDA officials walked through the soot-stained corridors still lined with fire hoses and covered with a half-inch of blackened water, checking on the animals and examining "sterile" laboratories to determine if they were affected.

"Our first concern was to separate the fire and the contamination associated with smoke from the areas occupied by the animals," said Richard J. Ronk, Miller's deputy.

Before they were evacuated, employes sealed triple doors on the fourth and fifth floors, directly above the fire, to prevent smoke intrusion into the areas where most of the animals are housed.

"Many of these experiments could not be easily duplicated," said Ronk, who mentioned tests on cheeses and how various materials affect animals genetically, among the experiments in process.

The fire destroyed ceiling panels along the east corridor of the 21-year-old building. Water leaking through the floor caused extensive damage in two laboratories below.

Battalion Fire Chief Robert L. Baker said firefighters were able to prevent the fire from spreading to an adjacent room containing a small quantity of radioactive material being used in laboratory experiments. "There was no exposure," he said.

About 200 employes working in the worst damaged areas were sent home about 2:30 p.m.

Ronk said the fire was the worst of many "minor fires that we've had in this building . . ." He said the building is "substandard, safetywise."

The agency has a nearly completed new laboratory in Beltsville and is scheduled to move next year, Ronk said.

The General Services Administration, the government's landlord, spent $30,000 last summer to upgrade the alarm system, a GSA spokesman said.