As the curly haired Libyan who has received political asylum sat sipping coffee in an Alexandria restaurant recently, he smiled when the phrase "stray dog" came up.

A favorite term of Libya's Col. Muammar Qaddafi for his opponents abroad, it represents the ultimate threat from the Libyan leader, who has said in numerous speeches that his countrymen in the United States who do not agree with him should be "liquidated."

Because of such threats, said the 29-year-old Libyan, who first came to the United States in 1974, he made the transition from visiting student to political refugee and businessman. "Qaddafi says, 'Those stray dogs abroad, they should not think their families or children will escape punishment,' and he proves he means what he says," he said. "There is an atmosphere of fear and intimidation."

His situation is not unique among the 6,500 Libyan-born residents of the United States, two-thirds of whom came to this country after Qaddafi took over in Libya in 1969. While most of them say they are not directly threatened by Qaddafi, a number express fear that criticism of him may mark them, or their families at home, as targets.

The Libyans are scattered across the United States, and there is no precise estimate of how many are in the Washington area, where most are believed to be college students. The Libyan government operates a center for college students in McLean, but there is no identifiable Libyan neighborhood in the Washington area and few of the Libyans here are willing to talk publicly.

"In Qaddafi's eyes, every Libyan who is outside the country without him knowing about it is part of the opposition and has to be liquidated," said Ala Senussi, a critic of the Libyan leader and an employe of an embassy in Washington.

"If you're on the hit list, what can you do?" said Aly Abuzaakouk, a 42-year-old Detroit resident who said he was told by the FBI that he was targeted by the Libyan leader in 1980. "You start to work with the sixth sense all the time."

Libya was one of five nations President Reagan cited recently as forming a terrorist network that he compared to "Murder Inc." The president branded the countries -- Libya, Nicaragua, Cuba, North Korea and Iran -- "outlaw countries . . . engaged in acts of war against . . . the United States."

Reagan administration officials say the activities of Qaddafi supporters in the United States are "a matter of great concern." One of the most recent indications of that concern came in May, when 16 Libyans were subpoenaed to appear before a federal grand jury in Alexandria investigating an alleged plot to assassinate anti-Qaddafi Libyans in the United States, according to sources close to the investigation.

The grand jury investigation, which a Washington lawyer for the Libyan government has called a "witch hunt," has not returned any indictments. Justice Department officials decline to talk about the investigation. A source close to the investigation, however, said that one of the 16 Libyans has left the country since the grand jury began meeting.

Richard C. Shadyac, the lawyer for the Libyan government, as well as the 16, who include several employes of the student center, has been informed by the Justice Department that they are targets of the investigation.

Fifteen of those subpoenaed in Alexandria hold student visas, according to the Immigration and Naturalization Service. The 16th, Mohammed Ayed, came here from Libya in 1961 and is a permanent resident, an INS official said. Ayed, who is employed at the student center, said he has not been notified that he is a target of the investigation.

Some Libyans say the FBI's surveillance of pro-Qaddafi Libyans is the reason that only one of the 30 assassination attempts that the State Department says have occurred against Libyans living abroad since 1980 has taken place in the United States. In 1980, a gunman shot a Libyan student in Colorado, leaving him blind in one eye.

The FBI is "doing a decent job," said one Northern Virginia Libyan, adding that Libyans feel safest in the United States. "Libyans now consider the United States the best place to be for security reasons, just looking at the statistics," he said.

Still, there have been incidents that have raised the concern of the anti-Qaddafi Libyans. Last year, two Libyans were arrested outside a Holiday Inn in Essington, Pa., after buying three .45-caliber handguns with silencers and two bulletproof vests from an undercover FBI agent. The INS said one of the Libyans was holding a student visa when arrested, but they have no record of when and how the second Libyan entered the United States. Both are serving prison sentences on firearms charges.

"Qaddafi spends more time on getting rid of his opponents than anything else," said Marius Deeb, a visiting professor of Arab studies at Georgetown University's Center for Contemporary Arab Studies. "I think he means business when he says he wants to kill his opponents . . . so I think they have a right to be scared."

The anti-Qaddafi Libyans have organized and begun holding unpublicized meetings. The anti-Qaddafi General Union of Libyan Students has met annually for the past four years, according to several sources. Last year, 300 people attended its conference in Colorado, according to Abuzaakouk. In addition, the National Front for the Salvation of Libya, a group of exiles dedicated to the overthrow of Qaddafi, publishes a newsletter out of Chicago.

Salem Zubeidy heads the People's Committee for the Students of Libyan Arab Jamahriya Inc., as the McLean center is called. A graduate student at the University of Michigan, Zubeidy, 37, declined through Shadyac to be interviewed for this story. But in a 1984 interview with The Washington Post, he said the center deals solely with student affairs, administering scholarships. He complained of "continuing harassment of Libyan students" by the U.S. government and said he believed that his "whole office is tapped."

After a dozen anti-Qaddafi students seized the student center in December 1982, Fairfax Commonwealth's Attorney Robert F. Horan Jr. said he and the FBI found no evidence of military purchases among the student files, as the anti-Qaddafi students had claimed.

Libyan dissidents such as Abuzaakouk, however, remain suspicious of the student center, charging that it is run by one of Qaddafi's "revolutionary committees" that issues "propaganda against Libyans abroad . . . to keep them from voicing opposition views."

There are 1,172 Libyans studying in the United States, according to the INS -- a drastic drop from the 3,000 who were here in 1980.

They have been less than welcome in some college courses since 1983. That year, the U.S. and Canadian governments, responding to fears that Qaddafi was attempting to acquire nuclear weapons, banned Libyan university students from studying aeronautical and nuclear engineering.

State Department officials are reluctant to talk about Libyan affairs. "Any time we go on the record characterizing anything one way or the other, someone could be hurt," one official said.