The Reagan administration is considering rounding up and expelling Libyan diplomats in Washington, according to administration sources.

Behind the prospective action, these sources say, is administration concern over Libya's military adventurism in Africa, Libyan support for international terrorism and the possibility that diplomats here might in some way try to eliminate Libyan exiles living in the United States who are foes of the controversial Libyan leader, Col. Muammar Qaddafi.

The U.S. government sources said that no final decision had been made on whether to move against the Libyans here, but that the situation has been under review for months and was now at the stage where various recommendations are being considered about what action, if any, to take.These sources suggested that a decision is very near, with one official saying it is "on the knife's edge," meaning that the decision could go either way.

Last year, eight Libyan expatriates living in Britain, Italy and Greece were murdered, and in October a Libyan student-dissident was shot and wounded in Colorado. In May, 1980, the British government expelled four Libyan government representatives, and four others were expelled by the U.S. government that same month for their alleged participation in a campaign of intimidation against exiled opponents of Qaddafi.

According to U.S. law enforcement sources, the FBI has been told that it might be called in to assist in the possible expulsion in a role similar to that played by the bureau when the Iranian embassy was closed here during the hostage crisis in 1979.

Although there are reports that Qaddafi is interested in improved relations with the United States, the Reagan administration has made the campaign against international terrorism a cornerstone of its foreign policy. It has been looking for ways to make its displeasure known to Qaddafi since the colonel's Soviet-equipped forces intervened in the north African nation of Chad, a move that has alarmed many nations in the region including U.S. allies in Egypt, Sudan and Nigeria.

In an interview in March with CBS-TV correspondent Walter Cronkite, President Reagan mentioned Qaddafi by name in conjunction with communist-bloc nations attempting to export terrorism to El Salvador.

The U.S. stakes in such a move against the Libyans could be extremely high, however, because the Libyans are the third largest supplier of oil to this country, providing about 11 percent of U.S. consumption. The United States, in return, puts about $12 billion a year into Qaddafi's treasury.

Though the United States has not officially broken diplomatic relations with Libya, Washington has had no diplomatic representatives in that country since May 1980. The U.S. embassy was sacked and burned in Tripoli in December 1979 by mobs shouting their support for Iran in the hostage crisis.

The Libyan diplomatic mission here, as in many other countries, has been called a "People's Bureau" since the embassy was taken by Libyan students at Qaddafi's instigation in September 1979.

Ali Ahmed Houderi, Libya's chief diplomat here, said yesterday he was unaware of any plans to close the embassy here. "We're not anticipating anything, but if anything should happen we would abide by it" and leave peacefully, he said. "If it were to happen -- God forbid -- we are not going to take it lightly," he added.

Houderi said Libya could deal with the severing of relations if it came to that, but questioned whether it would serve either country. The Libyan official, who said there are 60 to 70 people connected to the mission here, added that "we are doing everything humanly possible to insure better relations with the United States."

Last summer, in an effort to justify the assassinations in Europe and perhaps presaging a new wave of political murders abroad, Qaddafi was quoted as saying the "physical and final liquidation of the opponents of popular authority must continue at home and abroad. We fear no one."

Houderi took issue with administration claims that Libya plays a major role in fostering international terrorism. "We condemn terrorists," Houderi said.

He said critics fail to distinguish between Libya's support for national liberation movements, such as the Irish Republican Army, and random acts of terrorism. "We should not mix terrorism . . . with our support of liberation movements," he said.