The Shifa pharmaceuticals plant in Khartoum, Sudan, was destroyed last Thursday in a US Cruise missile attack at the same time that navy-launched missiles struck at a suspected terrorist base in eastern Afghanistan. In an echo of the controversy over the bombing of a purported baby milk factory during the Persian Gulf war, Sudanese officials have protested to the United Nations that the plant made medicine, not weapons.

Under pressure to back up its claim, the Clinton administration let US intelligence officials yesterday discuss some of the evidence that led to the decision to strike.

One US intelligence official, who spoke on condition of anonymity, said the physical evidence being cited repeatedly by Clinton administration officials is a soil sample ``obtained by clandestine means'' from inside the Sudan plant. The sample showed traces of a substance called empta, or o-ethylmethylphosphonothioic acid -- a material with no commercial uses that is a key ingredient of VX.

``Once you have it, you're a long way toward the production of VX,'' said the intelligence official. The material apparently got into the soil immediately outside the plant either through airborne emissions or spillage from the manufacturing process.'' The official did not describe how the soil sample was obtained.

``This is something we went out of our way to get,'' he said.

The administration also conceded for the first time, after eyewitness accounts from the smoldering ruins of the Shifa plant, that the facility probably also manufactured medicines.

``That facility very well may have been producing pharmaceuticals,'' State Department spokesman James Foley said. Among other things, the plant had been approved to produce medicine for shipment to Iraq under the humanitarian exception to the UN-imposed trade sanctions on that country.

``But that in no way alters the fact that the factory also was producing precursor elements,'' Foley said.

Last week, senior US officials who briefed reporters following the attack said they knew of no commercial products made at the Shifa plant. Eyewitness accounts by Western journalists who toured the wreckage, however, included descriptions of pills and medicine bottles strewn all over the site.

The US official said American intelligence has been monitoring the Shifa plant for more than a year, and developing information on its operations and leadership.

Intelligence gathered during this effort showed ties between senior executives of the plant and known terrorist groups, including the one headed by Osama bin Laden, the Saudi multi-millionaire believed responsible for the August 7 bombings of US embassies in Kenya and Tanzania, he said.

Intelligence also linked these executives with people involved in Iraq's weapons development, including Emad al Ani, known as the father of Iraq's chemical weapons programme.