RIO DE JANEIRO--Brazil's attorney general's office has ruled in support of a controversial new mining tax that has been charged by Minas Gerais, the country's biggest mining state, since April, Brazil's Valor Economico newspaper said Thursday. The attorney general's office, which advises federal government departments on legal issues, was invited by the Supreme Court to give a formal opinion on the charging of the state-level tax, Valor said, citing a lawyer from the country's National Industries Confederation, or CNI, which is contesting the charges. The Supreme Court is considering a case filed by CNI against the charging of state-level taxes on mining in the country's Minas Gerais, Para and Amapa states. CNI claims the new charges are unconstitutional since mining royalties are already charged by Brazil's federal government, which pays out part of the total royalties it receives to governments of the states and municipalities where mines are located. The new state-level charges would represent additional annual revenue for the states of around 500 million Brazilian reais ($246.30) in Minas Gerais state, BRL800 million in Para state and BRL150 million in Amapa state, according to Valor. The attorney general's office said the governments of Brazil's mining states have constitutional rights to charge taxes that will cover the cost of supervising mineral research and production activities, to participate in production revenues and receive compensation for damage caused by mining activities in the states, according to the report. -Write to Diana Kinch at diana.kinch@dowjones.com Subscribe to WSJ: http://online.wsj.com?mod=djnwires