James P. Akin, an official in the Alexandria school system since 1966, said yesterday that it has been well known among school officials for years that there were great disparities between the achievement test scores of blacks and whites.

But not until yesterday, when school Superintendent Robert W. Peebles announced that blacks lagged behind whites an average of 37 percentile points on the composite scores of the Science Research Associates exams, was the gap publicly disclosed.

The reason, Akin said, was that school officials feared being called racist.

"It was a high public relations risk to release the results by race ," said Akin, the schools' director of research, planning and evaluation. "Finally, we have let the black underachievement out of the closet."

Black community leaders' reaction to the wide disparity between the scores of black and white students was guarded yesterday, with many seeming to be wary of what prompted school officials to suddenly release the test results by race.

"I don't see it [Peebles' announcement of the racial breakdown] as being racist per se," said Gilbert Mays, president of the NAACP's Alexandria chapter. "If it's given for the right reason, to face up to a problem and help kids . . . . but it could be construed as racist if given just to compare."

James M. Patton, director of teacher education for the Virginia Department of Education, said these disparate numbers "can play into the hands of people who are racist."

Patton, who is black, said he is uncertain whether releasing the breakdown is a good idea. "Only the results will tell," he said.

Akin said school officials finally decided to make the scores public so that they could, first, collect data on the problem of lower black test scores; second, discover the roots of the racial disparity, and third, attempt to solve it.

So far, the data show that of the nine grades tested, blacks trailed behind whites on the combined SRA math and verbal test scores by 37 points.

In 11th grade, the year showing the most significant gap, black students in Alexandria earned an average score of 27 points, meaning they scored higher than 27 percent of the million-plus students nationwide who took the 1984-85 SRA test. Eleventh grade Alexandria whites averaged 75 points, a disparity of 48 points.

Discovering the root of the alarming disparity will be difficult, school officials and black community leaders say.

Local, state and national educational analysts say that scores showing lower scores among blacks really highlight the disadvantage of low-income people, not merely blacks.

Many black students start out behind because they don't attend preschool, and are not coached and motivated by their parents, as many middle-class white children are, Mays said. "They start out behind and often continue to stay behind."

Akin believes black children also are deprived of the abundance of role models that white children have. "How many black dentists do the kids see?" Akin asked. "They see preachers and teachers. They think they have to be Martin Luther King or Jesse Jackson to succeed and there's nothing in between."

Peebles said he will meet with teachers, counselors and administrators on Monday to discuss ways to narrow the test score gap. Among the ideas to be discussed will be the inclusion of black community leaders in the classroom and as tutors on reading projects, and improving the teacher-student ratio in remedial programs.

Said Peebles, "It's going to take some time, but we've got to get started."