Anxious to show its mettle and advertise its anger, the Carter administration has decided to make deep cuts in the modest U.S. aid program for Afghanistan, the mountain nation whose police stormed a hotel room where rebels held the U.S. ambassador, who was killed in the incident.

The killing of the ambassador, Adolph (Spike) Dubs, has strained Soviet-American relations because the United States is convinced that Soviet advisers to the Afghan police refused to heed the pleas of U.S. diplomats on the scene. The diplomats, seeking to save the ambassador's life, had urged negotiations with the unidentified rebels who had seized him.

The Afghan government and the Soviet government news agency, Tass, have both denied that Soviet advisers were involved. But Carter administration officials, basing their views on detailed eyewitness accounts from U.S. diplomats in Kabul, Afghanistan's capital, believe otherwise.

U.S. sources yesterday provided the text of those eyewitness accounts to The Washington Post. They are described in an accompanying article.

The decision to make deep cuts in the U.S. aid program -- which totals just $14.8 million this year -- was made known yesterday by high-level administration officials.

These sources said the United States had been considering aid cuts for Afghanistan before Dubs was killed, in part because of the "abysmal human-rights record" of the leftist Afghan regime, in the words of one official, and in part to protest the difficulties Washington has had in dealing with the authorities in Kabul.

The White House is expected to announce the aid cuts today or tomorrow. The exact dollar figure had not been determined last night, but officials said it would probably be more than half the total.

These officials said they did not want to eliminate the aid program entirely, because they want to keep "a line open" to the Kabul authorities, and also because some of the aid program is strictly humanitarian in nature.

Further emphasizing their anger over the Dubs slaying, American officials yesterday made known new details of the diplomatic protes on the incident delivered Feb. 14 by Deputy Secretary of State Warren Christopher to the Soviet ambassador, Anatoliy F.Dobrynin.

Christopher is said to have told Dobrynin that the involvement of Soviet advisers in the Kabul shootout could have serious consequences for Soviet-American relations.

Those relations are already tense because of the Chinese invasion of Vietnam, which followed soon after the visit to the United States of Teng Hsiao-ping, the Chinese leader. Official Soviet press commentaries have suggested that the United States might have been involved in China's decision to move against Vietnam.

This is a delicate moment in Soviet-American relations, because a new strategic arms limitation treaty (SALT) is all but completed. The United States hopes that a positive Soviet reply to American proposals made last week could wrap up the SALT pact, but so far the Soviets have not responded substantively to those proposals.

Christopher reportedly emphasized to Dobrynin that the United States was not accusing the Soviet advisers of responsibility for Dubs' death, but rather was criticizing what American diplomats on the scene felt was an unhelpful attitude.

Christopher is said to have given Dobrynin extensive details from the eyewitness accounts of the incident that the U.S. embassy in Kabul cabled to Washington.

Christopher reportedly told the Soviet ambassador that the refusal of Soviet advisers to consult with U.S. diplomats in Kabul was inexcusable. Christopher is also said to have asked Dobrynin for a full account of the Soviet advisers' role -- an account that has not yet been provided, U.S. officials said last night.

Dobrynin expressed condolences to Christopher on Dubs' death, noting that he had known Dubs personally and regretted the killing of a fellow ambassador.

The Carter administration has not yet informed Afghanistan of its plans to cut the U.S. aid program, officials said yesterday. The largest element in the program consists of $11.7 million in aid to education and other "human resources development." The administration had planned to ask for an increase of about $2 million in the program for next year, including a $9.7 million project for aid to agriculture, rural development and nutrition.

Soviet aid to Afghanistan is many times larger, totaling more than $100 million, according to U.S. officials. Afghanistan has moved into an intimate relationship with the Soviets since a coup last year installed the new leftist regime. The intimacy of the Kabul-Moscow connection has contributed to the deterioration of U.S.-Afghan relations, U.S. sources said.