Daoud Salahuddin, whom police yesterday accused of killing the leader of an Iranian group opposed to Ayatollah Ruollah Khomeini, is one of a small, militant circle of black American Muslims who have fervently adopted the Khomeini brand of revolutionary Islam.

Many of them, including Salahuddin, were drawn into the group while attending Islamic discussion sessions led by Ali Agah, the head of the Iranian Embassy delegation who was expelled along with his staff in April by President Carter.

Serveral served as guards at the Iranian Embassy before the expulsion. Some later joined in efforts to expand the influence of pro-Khomeini Muslims at the Islamic Center, the long-placid spiritual home of Washington's 50,000-member Islamic community.

With the departure of the Iranian diplomats, many gathered around Bahram Nahidian, a 41-year-old Georgetown carpet dealer who in the months after the overthrow of the shah has become the inspirational force behind the supporters of the Iranian revolution here.

Today, the blacks see themseleves as foot soldiers fighting a battle against the great American Satan 6,000 miles from the wellspring of their faith in Tehran.

The blacks are involved "because it is a communality of oppression," said Kwasi Lumumba, a former black power activist who now is a regular in the black Islamic community here. "Like the blacks in the 1960s, the Muslims of the world are oppressed. You see the same slogans, the same aspirations, the same desires. It's an overriding desire to change the moral fiber of society."

"It's a universal tenet of the religion -- to unite and struggle against the oppressors, against the nonbelievers," he said.

The blacks in the circle form a loose federation rather than a tightly knit group, according to D.C. police. Only a few apparently have ties to the World Community of Islam in the West -- known in the past as Black Muslims.

Salahuddin is the only one of the three named suspects in Tuesday's killing of Ali akbar Tabatabai clearly known to be a Muslim. Yet, police and many Muslims believe that the shooting is related to the political turmoil that recently has shaken the Middle East and spilled over into other world capitals, including Washington.

Thought their numbers here are small -- estimates range from 10 to several dozen -- these American blacks have made their weight felt in local Islamic circles, thanks largely to the leadership of Nahidian, a naturalized American citizen who is acknowleged by all as the most prominent supporter in this country of Khomeini.

It is not a group that has endeared itself to the majority of Muslims here, however. Fearful that many Americans have come to see Islam as a radical tool of revolution, many feel the Nahidian-inspired Muslims are further tarnishing their religion.

In one incident last spring, several supporters of Khomeini scuffled with leaders of the Islamic center over proper attire for women, wrenching the neck of one of the center's officials. Several non-Iranian Muslims claimed that they disrupted prayer services with their demands for a voice in center policy.

For the past eight months, D.C. police have been investigating the activities of a small sub group that calls itself the Islamic Guerrillas in America, which they believed to be involved in the strife at the center. Police sources say Salahuddin is a member of the guerrilla organization, a Washington-based, cadre of Muslims suspected of planning terrorist acts to further adherence to strict Islamic discipline.

There are those at the Islamic Center who accuse Nahidian of encouraging such incidents as part of a move to align the center more closely with the Ayatollah's policies and interpretations of Islamic law. One of Nahidian's critics, Ezzart M. El Dak, an Egyptian who runs a clothing shop on Capitol Hill, said he believes Nahidian has recruited American blacks to the center in an attempt to swell his power base.

"Nahidian gave wrong information to the American brothers," El Dak said. "He brought them in here to catch them like fish. I was worried that this would happen, that the American brother is used in a bad way."

El Dak said Salahuddin was coaxed into the pro-khomeini group by Nahidian shortly after the Iranian embassy was closed. Nahidian gave the American blacks free room at the Islamic House, a building Nahidian once owned but now says he cares for as part of a nonprofit Islamic education effort, and also let them use his car.

Nahidian, interviewed yesterday at the Islamic Center, said his recruiting efforts were color blind. He said he was no closer to Salahuddin than he was to the other Muslims at the center, and denied that he is a leader of any group or segment. He characterized the charges against Salahuddin as harassment.

"He was not involved," Nahidian said. "Islam does not allow you to go ahead and kill someone unless the Islamic Court approves it, and he is a good Muslim. He's good brother."

Despite Nahidian's denial that he was close to Salahuddin, the two were arrested together in New York on Nov. 4, the day the American hostages were seized in Tehran. Nahidian, Salahuddin and five others briefly took over the Statue of Liberty and unfurled a banner down its 22-story side.

Salahuddin stayed for a time at the Islamic House. Until recently, the building was the site of large prayer gatherings attended by many black American Muslims, neighbors said, but the numbers dwindled and the prayer services no longer are held there.

Nahidian said Salahuddin believes the same doctrine as the other Muslims at the center -- that there is no difference between being a muslim and being pro-Khomeini.

"All of us are pro-Khomeini. There is none of us who are anti-Khomeini. Khomeini hasn't done anything to the Muslims. He's done something to U.S. imperialism."

Nahidian's stress on Khomeini was a major cause of the rift between him and other Muslims like El Dak, who insisted that Islam should not focus on nationalism or on one particular leader.

Some black Americans at the center have stayed outside of the conflict. One of the, who declined to give his name, characterized himself as part of the "silent majority."

He attributed the differences between Nahidian and other Muslims to the larger age-old struggle between Sunni and Shiite Moslems that came to world attention during the Iranian revolution. Nahidian is a Shitte, a sect that stresses the teachings of one descendant of Mohammed over others. Moslims from other nations are largely Sunni and interpret the Koran to teach that no person should be elevated above others in Islam.

The black American said he believed the differences between the two sects may have led the non-Iranians to read dark motives into Nahidian's attention to "the American brothers."