A record 96.6 percent of Virginia 10th graders passed this year's basic skills examination in reading and mathematics that is required for graduation from high school, according to figures released yesterday by the state Department of Education.

Black students continued to score below white students, but the gap between them is shrinking because the scores of blacks are improving, the test results showed.

Students in several Northern Virginia jurisdictions surpassed their counterparts statewide: in Loudoun County, the pass rate was 99.3 percent; in Fairfax County it was 97.6 percent, in Falls Church, 97 percent, and in Prince William, 96.8 percent.

But others fell behind, including Arlington, at 95.5 percent, Manassas Park, 89.8 percent, and Alexandria, 87.4 percent.

Manassas students were equal to the state average.

Alexandria's failure rate was third highest in the state, behind only two rural counties, Greensville and King and Queen.

The minimum competency examinations measure basic skills in reading and mathematics, such as using reference sources and reading maps. Students first take the test in 10th grade and are required to pass it to graduate from high school. If they fail in 10th grade, they are given remedial help and may retake the test in the 11th and 12th grades.

Of the 81,939 public school students who took the test in February, more than 68,000 were 10th graders.

Virginia established the test requirement in 1981 as part of a national trend stemming from public concern about the quality of public education. Maryland also requires students to pass reading and mathematics tests to graduate from high school, and is phasing in a requirement that they pass citizenship and writing tests as well.

Virginia's scores have risen steadily since 1978, when students began taking the test without its being a graduation requirement. The first year, 82.2 percent passed both the reading and the mathematics sections.

But some gaps remain. White students pass the test at a higher rate than blacks -- 97.7 percent to 93.4 percent this year, although the difference is narrowing from the 1978 figure of 89.1 percent to 58.2 percent. More girls than boys pass -- 97.5 percent to 95.7 percent this year. Students in wealthier school systems are more likely to pass.

Of the high school juniors who took the test this year, 92.7 percent passed both the reading and the mathematics sections. For seniors, 87.4 percent passed both. Some of the juniors and seniors were retaking the test; while others, new to the state, were taking it for the first time.

The test also is administered to handicapped students, and 48.2 percent passed both the reading and mathematics sections this year. The pass rate for handicapped students has increased in the last several years; students who do not pass are eligible for a special diploma.