A proposal to offer a special math and science curriculum to teen-agers in the growing upper part of Montgomery County has alarmed educators and parents at the county's opposite end, who predict it would drain white students from the county's only high school desegregation effort.

Although the program would provide sophisticated math, science and computer courses for just 400 of the county's 96,000 students, the proposal has broad ramifications because it throws into conflict two of the school system's main priorities: providing new services to a growing population in the outer suburbs, while fulfilling a promise to achieve integration in its older, heavily minority communities.

The conflict, which involves Gaithersburg High School and Montgomery Blair in Silver Spring, illustrates the political problem of trying to create popular magnet programs to attract white students to heavily minority schools, while not shortchanging other schools.

Parents from the northern part of the county believe their children deserve easy access to advanced programs such as the one at Blair. But those in the southern part fear that a rival program would lure away some white students who have helped desegregrate Blair, a 65 percent minority school.

"It's a hard issue, a very hard issue," said Blair Ewing, a school board member.

School Superintendent Harry Pitt is expected to tell the school board next week whether he favors the proposal, from a committee of administrators and parents, to renovate part of Gaithersburg High at a cost of $1.5 million, to set up a rigorous, technical education program for especially bright students.

School officials are committed to providing a full array of services to children of the county's rapidly growing northern section, where parents and administrators have complained about lack of access to special programs. At the same time, Montgomery school officials are striving to improve the level of desegregation at a time when minority enrollment has tripled during the last 15 years. Minority children now make up about 33 percent of the school enrollment, with the greatest concentration in the southern part of the county.

The Blair magnet, which began to be phased in two years ago, is intended to attract white students to the 65 percent minority school by offering a rich blend of math, science and computer classes. The program enrolls 214 ninth-, 10th- and 11th-graders. One-fifth of them come from the upper part of the county that would be served by the Gaithersburg program.

"It becomes somewhat emotional in the sense of one part of the county wanting something and another sector fearful it will be hurt," said school board member Bruce Goldensohn, the only one of the board's seven members who lives in the upper part of the county.

Pitt was unavailable for comment yesterday, but William Henry, the school system's spokesman, said he believed the superintendent had not made up his mind and would not discuss the matter publicly until he meets with the board on Tuesday.

The Gaithersburg proposal calls for an intensive, interdisciplinary program -- similar but not identical to Blair's -- that offers students a chance to study advanced math, computer science and foreign languages and to perform scientific research.

The committee was assigned a year ago to develop the proposal by former school superintendent Wilmer S. Cody, who sought to alleviate a widespread concern among residents of the upper county that their schools do not offer as many kinds of academic specialties as the older, more developed parts of the county. A survey of parents there, conducted by the school system in 1985, showed that the most popular special high school curriculum would be a math-science-computer science program.

"With Montgomery having as much of its tax base in technical fields, the school system is going to have to understand, if they are going to keep the good kids they've got, and attract families that have a technical bent, they are going to have to provide the technical schools," said Holly Geddes, a mother of three sons who has been urging school officials to open the program in Gaithersburg, where she lives.

Although the Blair program is open to students from throughout the county, Geddes and other parents from the upper county say they are reluctant to send their children there because it would require an hour-long school bus ride each way and cut into their extracurricular activities.

But for parents and educators in the southern part of the county where the concentration of minority students is greatest, the Gaithersburg proposal looms as a threat to the program at Blair.

"I think it would have great difficulty surviving," said Sandra Robinson, the school system's coordinator of magnet schools. "We should give Blair High School a chance to prove itself, and we haven't done that yet."

She noted that Blair, which was expected to attract 100 students per year to its math-science program, has not yet received that many qualified applicants.

She and other educators predicted the magnet program will not become more popular until it graduates its first students, thus providing county parents with evidence of improved scores on college-entrance tests and enhanced ability to attend good universities.

Kay Meek, who lives near Blair and was the committee's representative from her part of the county, predicted a math-science program at Gaithersburg would drain Blair of white students at a time when the "magnet" has not yet enabled the school to attain its goal, set by the school system, of becoming 50 percent white.

Some students who travel to Blair from the upper part of the county said they wouldn't trade schools to attend one closer to home.

"It is like saying I would root for the Dallas Cowboys when I really want to root for the 'Skins," said Shane Cohen, 15, a sophomore who travels an hour each way to Blair from his home in Damascus. "All my friends are at Blair. It is my school."

In recommending the Gaithersburg program, the committee acknowledged it would have an effect on Blair. But Janet Garrison, the chairwoman, said, "We do not feel there will be a significant negative effect that will cause its demise." In an attempt to blunt the drain of white students from Blair, the committee recommended that the only white students to be allowed in the Gaithersburg program be those from the surrounding area.