A federal appeals court has upheld the constitutionality of Virginia's abortion law, rejecting claims by antiabortion protesters who conducted repeated demonstrations at a Northern Virginia abortion clinic.

The decision by the 4th Circuit Court of Appeals in Richmond stemmed from a continuing clash between abortion opponents and the Northern Virginia Women's Medical Center in Fairfax County. The center has been the scene of arrests, demonstrations and controversy for several years.

"First trimester abortions are the only type at issue in this case. The Virginia statute pertaining to them conforms to the constitutional principles expressed in [a 1973 U.S. Supreme Court decision]," the three-judge appeals panel said. Its ruling was issued Friday and made public yesterday.

Lawyers affiliated with the American Civil Liberties Union of Virginia, which represented the medical center, said they were pleased by the decision. A woman's right to an abortion "was affirmed against interference" by protesters, said Leonard Rubenstein.

William E. Findler, a lawyer for the antiabortion protesters, said yesterday he was uncertain whether the decision would be appealed. Other lawyers representing demonstrators could not be reached for comment.

The antiabortion activists had sought a court order barring the medical clinic from performing abortions, arguing that abortions are unconstitutional.

In rejecting their contentions, the Richmond appeals court cited the 1973 Supreme Court decision that held any abortion during the first trimester of pregnancy should be left to the judgment of a woman and her doctor.

The appellate court upheld several orders issued by U.S. District Court judges in Alexandria. The federal judge prohibited antiabortion protestors from trespassing at the medical center and imposed $500 fines against four demonstrators in 1978 for contempt of court.

Demonstrations against the clinic have continued, including a protest last September by more than 500 abortion opponents. There were no arrests during the Sept. 8 demonstration.

Fairfax County judges and prosecutors were also drawn into the controversy.

After Virginia's abortion law was held unconstitutional by one Fairfax judge, county prosecutors temporarily decided not to bring charges against antiabortion protestors. Officals told the appeals court in Richmond, however, that this policy is no longer followed.

In their legal arguments, the abortion opponents contended that the courts have erred by failing to consider the issue of when human life begins. The Supreme Court has said it "need not resolve" this question.