The Defense Department has granted top-secret security clearance to citizens of countries that oppose the national interests of the United States, in violation of Pentagon regulations, according to a report by a congressional subcommittee.

The study, conducted by the House Armed Services investigations subcommittee for Rep. Bill Nichols (D-Ala.), randomly selected 310 Pentagon employees with security clearances and found that 49 were legal aliens born in one of 29 countries the subcommittee designated as opposed to U.S. interests.

The report also charged that Pentagon records of security clearance checks are at times inaccurate and confused. It says, among other things, that no definitive information could be obtained on 41 of the 310 people who were initially identified as non-U.S. citizens.

More than 23,000 people from the 29 countries work for the Defense Department, the report said. This includes 5,186 born in China, 3,746 in Vietnam, 3,623 in Cuba and 1,883 in the Soviet Union.

Defense Department spokesman Jim Turner said the subcommittee did not conduct a complete review of agency personnel files. "The report contains several erroneous conclusions based on an apparent fundamental misunderstanding" of the agency's security procedures, he said. Turner would not elaborate on the misunderstandings.

In January 1987, the Defense Department enacted a regulation that only people who have been citizens for at least five years or those who have lived in the United States for at least 10 years may be granted security clearance.

Under the procedure, a waiver may be granted, but the study found that no exemptions had been sought for these workers.

The study examined Pentagon employees with "secret" or higher security clearance.

Those with secret security clearances came from China, Cuba, Nicaragua, Vietnam, Soviet Union and other countries with ties to the Soviet Union. The report said that, among other things, non-U.S. citizens are employed as an aircraft weapons specialist, as senior engineers on the F16 fighter project and as a specialist at an Air Force Distant Early Warning Line radar site, the first line of radar defense against a possible Soviet nuclear attack.

Rep. John R. Kasich (R-Ohio), who requested the report, said, "This is something we should be concerned about. It appears that there has been in the past a casual attitude toward {security clearance.}"

The report also found that the Defense Department's data base was at times incorrect or incomplete. An initial search of the Defense Manpower Data Center (DMDC) found 110 of 310 individuals from the designated countries were not U.S. citizens. However, in a cross-check with the military services, only 49 could be confirmed as non-U.S. citizens and 20 were naturalized citizens.

The report said, "We found individuals with security clearance on record at DMDC and not on record with the services," as well as the reverse. The study said probers found "data incorrectly recorded, Social Security numbers incorrectly recorded and data that indicates individuals are native-born U.S. citizens when, in fact, they are foreign-born."

In 1985, more than 5 million people held clearances for classified information, the report said.

The subcommittee said that among its discoveries were:The Defense Investigative Service had no records on two individuals in the Air Force, one born in Nicaragua, who have top secret clearances, and another born in Laos with a secret clearance. Two Air Force personnel born in the Soviet Union and one in Cuba hold clearances based on 1960s background investigations. An Army employee born in Cuba was granted top secret clearance in 1983 based on a security check conducted in 1970.

Allan Adler, legislative counsel for the American Civil Liberties Union, said, however, "The simple fact that an individual is born in a foreign country -- even a country whose government is hostile to the United States -- should not in and of itself raise questions as to that person's trustworthiness."