The leaders of an anti-tax revolt in Fairfax County were dealt another in a series of setbacks yesterday when a Circuit Court judge ruled that petitions they collected in a bid to change the county's form of government now belong to the court and cannot be returned to them.

Unless overturned on appeal, the decision by Judge Thomas J. Middleton means that Frederick T. and Marcia Dykes, founders of Citizens for Sensible Taxation, will have to start from scratch and collect about 50,000 new signatures if they want to force a referendum.

Frederick Dykes said his group probably will not appeal the case to the Virginia Supreme Court because of the cost.

The Dykeses launched a referendum drive last year to change Fairfax's form of government as a way to protest high taxes.

The group's ultimate goal was to win legislation limiting increases in individual real estate tax bills to 5 percent a year and freezing property taxes for people over 65.

To force the referendum, the group needed petitions signed by 10 percent of the county's registered voters, or 40,589 signatures.

Although they collected close to 50,000 signatures, the county registrar concluded that many were invalid, and Middleton ruled that the petitions fell 778 signatures short.