Virginia election officials announced today that they will proceed with plans for the Nov. 3 state legislative elections under a controversial reaportionment plan, despite the possibility that it could be declared invalid before the elections.

State Board of Elections Secretary Joan S. Mahan said that elections will be held as planned even though the House of Delegates' recent reapportionment is being challenged by more than a dozen groups in the courts and before the Justice Department as a violation of the Voting Rights Act. a

Mahan's statement today was supposed to eliminate widespread confusion over when -- and under what rules -- elections for the 100 House seats will be held. But Mahan said she could not rule out the possibility that either Justice or the courts could reject the plan later in the summer -- thus causing the elections to be postponed.

"We're following the law of the commonwealth," she said. "I don't think we have any other options." Opponents of the reapportionment plan have charged that it cannot be put into effect until it receives the approval of the Justice Department under the Voting Rights Act.

Many Northern Virginia politicians saw today's announcement as a victory for their efforts to enhance the clout of their rapidly growing region, which will gain two new House seats under the plan. "This ensures that Northern Virginia will receive its rightful share of delegates," said Del. David Speck (R-Alexandria). "So this is a good decision."

But opponents of the plan predicted that the state's decision to proceed will ensure only a postponement of the fall elections -- possibly until next year -- with no assurance that Northern Virginia will be able to keep the new delegates it picked up in a spring redistricting session.

"This will only cause more turmoil," said Stephen Bricker, an attorney for the American Civil Liberties Union. "They're the state just getting out further and further on thin ice instead of running to shore."

Under the schedule set in motion by today's action, candidates for the House seats must file for election by Aug. 7. Primaries were set for Sept. 8 in localities where political parties request them.

Members of the three-judge federal panel that is hearing challenges to the reapportionment plan had refused requests to issue a specific order that the elections be held under the new plan. The panel will hold its first hearing on the case Aug. 13, six days after the primary filing deadline.

Mahan has warned that the elections will have to be postponed until Dec. 29 if the judges then reject the plan.

Some political analysts say any postponement would do the most damage to the General Assembly's Democratic majority, which was responsible for the plan, which some opponents say contains legislative districts that vary too widely in population to win court approval. "There's some poetic justice there . . .," said Paul Goldman, a Democratic Party activist.

The Northern Virginian most immediately affected by today's decision is likely to be Democratic Del. Elise B. Heinz, whose Arlington-Alexandria district was abolished under the new plan becuse of population losses in the inner Washington suburbs. Heinz is planning to challenge Arlington's thre incumbent Democrats for the county's three remaining House seats.

The plan that was reaffirmed today adds two seats to Fairfax County's 10-member delegation and one to Prince William County's, giving Prince William three delegates of its own instead sharing three with Loudon County. w

Most of the General Assembly's Democratic leaders have been pushing to keep a 10-year-old plan in place for the November electons, despite protests that such a move would save the seats of many incumbents at the expense of rapidly growing localities.

Today's decision may also trigger legal challenges from politicians in suburban Richmond's Henrico County, who argue that the state's lawyers improperly changed the House plan after it left the General Assembly.

The revision, which subtracts House representation from Henrico and gives it to other suburban Richmond counties, was announced last month after attorneys polled members of the General Assembly by telephone.

"For a legislative body to operate by a telephone poll of the members to me is simply ridiculous," said Del. Ralph L. Axselle Jr. (D-Henrico). "I'm sure it will be challenged."