The Loudoun County school system has restricted parents' ability to remove their children from sex education and related lessons, a practice that a state official and some parents say may conflict with Virginia law.

Under a new county policy, topics related to sex education that were being taught before state-mandated standards took effect this year must be attended by all students.

At Tuesday night's Loudoun School Board meeting, four parents challenged the practice, claiming state law and Virginia Department of Education regulations allow parents to remove their children from parts or all of the Family Life Education program.

The "opt out" program was offered as a compromise to gain legislative approval for the statewide sex education curriculum, which mandates sensitive matters such as contraception as well as topics such as leadership and family values.

State sex education coordinator Jeane Bentley said yesterday she believes local school systems must allow students out of any part of the sex education curriculum -- new or old -- when so requested by parents. "It would take state Board of Education action" to change the policy, she said.

The new parts of Loudoun's sex education curriculum supplement previously taught lessons and reflect few changes in emphasis, school officials say.

Waterford resident Barbara Chauncey, a sex education opponent, said Tuesday the issue now is not the merits of the program, "but rather the right of every parent to choose the education that best meets the needs of their own children."

The Loudoun School Board voted unanimously Tuesday to ask the state for a ruling on the legality of the policy, which would exclude about 70 percent of the sex education program from parental option. But the board did not extend county parents' deadline of next Tuesday for requesting removal of children from certain lessons.

Children removed from the classes are to be given alternative lessons outside their regular room when their classmates take up sensitive topics.

Some school systems, including Loudoun, spread the sex education program throughout the curriculum. Many, including neighboring Prince William County, combined all sex education and related lessons into categories, which makes it easier to remove students from objectionable lessons.

Last school year, some officials in Loudoun and other school systems told parents that removing their children from sex education would deny them basic education. Even so, about 7 percent of the Loudoun student body was excluded from part or all of the program by parents.

In reaction to numerous complaints about opt-out procedures, Loudoun officials tried to find ways to handle the exclusions without denying routine lessons. School administrators said a state school official had initially approved the new policy but they have since been told it may not be acceptable.