RICHMOND, Va. -- A federal appeals court ruled Monday that Virginia's same-sex marriage ban is unconstitutional, the latest in a string of decisions overturning bans across America.

A three-judge panel of the 4th U.S. Circuit Court of Appeals in Richmond ruled that state constitutional and statutory provisions barring gay marriage and denying recognition of such unions performed in other states violate the U.S. Constitution. The Virginia gay marriage case is one of several that could go to the U.S. Supreme Court.

Gay marriage proponents have won more than 20 legal decisions around the country since the U.S. Supreme Court last year struck down a key part of the Clinton-era federal Defence of Marriage Act. Those rulings remain in various stages of appeal.

More than 70 cases have been filed in all 31 states that prohibit same-sex marriage. Nineteen states and the Washington capital district allow such marriages.

It was not immediately clear if or when Virginia would need to begin issuing marriage licenses to same-sex couples.

Virginia's same-sex marriage bans "impermissibly infringe on its citizens' fundamental right to marry," Judge Henry F. Floyd wrote in the court's opinion.

In February, U.S. District Judge Arenda Wright Allen ruled that Virginia's same-sex marriage ban violates the U.S. Constitution's equal protection and due process guarantees. Lawyers for two circuit court clerks whose duties include issuing marriage licenses appealed. Attorney General Mark Herring, representing a state official also named as a defendant, sided with the plaintiffs.

"Marriage is one of the most fundamental rights -- if not the most fundamental right -- of all Americans," David Boies, an attorney for the plaintiffs, said in a statement. "This court has affirmed that our plaintiffs -- and all gay and lesbian Virginians -- no longer have to live as second-class citizens who are harmed and demeaned every day."

In 2006, Virginians voted 57 per cent to 43 per cent to approve the constitutional amendment banning gay marriage. Virginia laws also prohibit recognition of same-sex marriages performed in other states.