President Clinton yesterday banned all commercial and financial dealings between the United States and Afghanistan's ruling Taliban militia, accusing the Taliban of continuing to provide refuge to Osama bin Laden, the wealthy Saudi exile suspected of ordering last year's U.S. embassy bombings in Kenya and Tanzania.

Clinton's executive order freezes all Taliban assets in the United States, bars the import of products from Afghanistan and makes it illegal for U.S. companies to sell goods and services to the Taliban, whose militant Islamic fighters control about 85 percent of the mountainous, war-torn country.

But the order makes an exception for food and other humanitarian supplies, and a senior State Department official emphasized that the sanctions are "not aimed at the people of Afghanistan."

U.S. officials said the measure is intended to put pressure on the Taliban to surrender bin Laden, who is accused of masterminding the Aug. 7 bombings in Dar es Salaam, Tanzania, and Nairobi, Kenya, that killed 12 Americans and nearly 300 Africans and wounded thousands more. Days after the attack, the United States launched cruise missiles at targets inside Afghanistan that officials described as bases used by bin Laden and his group of armed Islamic extremists, al Qaeda.

"The Taliban continues to provide safe haven to Osama bin Laden allowing him and the [al Qaeda] organization to operate from Taliban-controlled territory a network of terrorist training camps and to use Afghanistan as a base from which to sponsor terrorist operations against the United States," Clinton said in a letter to Congress explaining his order, which was signed on Monday and went into effect at midnight last night.

A Taliban official reached yesterday in New York, where the organization maintains a mission to the United Nations, reiterated the group's statements that bin Laden has either left the country or gone into hiding.

"We do not know his whereabouts," said the official, who spoke on condition of anonymity. If the Clinton administration is so certain that bin Laden remains in Afghanistan, the official added, "they have to prove it."

A State Department official, who also requested anonymity, said the Taliban's denials are "not credible." The official added, "We think there's a symbiotic relationship--he provides [the Taliban with] financing and fighters, they provide a safe haven for him and his agenda."

Citing intelligence reports, U.S. officials said there are indications that bin Laden's group has shifted people and equipment in preparation for another attack on American interests. The recent closing of a half-dozen U.S. embassies in Africa is directly related to that threat, they said.

Clinton's order does not address trade between Afghanistan and other countries, and its immediate effect is likely to be modest. Last year, the total trade between the United States and Taliban-controlled portions of Afghanistan was just $24 million.

On the other hand, a senior State Department official said, the order will block several incipient deals between the Taliban and U.S. telecommunications and pipeline firms. "The message," the official said, "is that the Taliban face a very bleak future and increasing international isolation so long as they shelter terrorists like bin Laden."

CAPTION: U.S. officials said the measure is intended to pressure the Taliban to surrender Osama bin Laden, suspected of ordering last year's U.S. embassy bombings.