U.S. deep-sea explorers must turn over to the Spanish government 17 tons of silver coins and other treasure recovered from a sunken Spanish galleon in 2007, a federal appeals court ruled Wednesday. But Tampa, Fla.-based Odyssey Marine Exploration has vowed to continue the protracted legal battle over the cache, which could be worth as much as $500 million. In a statement Wednesday, the company said it would take the next step in the appeals process, requesting a hearing before all the judges of the 11th Circuit Circuit Court of Appeals. That came after a three-judge panel of the 11th Circuit had issued its ruling in a case that could case spill over to treasure hunts for years to come. "We are certainly disappointed by the 11th Circuit's ruling," said Melinda MacConnel, Odyssey's vice president and general counsel. "We believe the U.S. Constitution and all other applicable laws give jurisdiction to the U.S. courts to determine the rights of Odyssey, Spain and all other claimants in this case." Attorneys for Odyssey asked the three-judge panel to overturn a lower court ruling and uphold the "finders keepers" rule that would give the treasure hunters the rights to coins, copper ingots, gold cufflinks and other artifacts salvaged in April 2007 from the galleon found off the coast of Portugal. Spain's lawyers countered that U.S. courts are obligated by international treaty and maritime law to uphold Spain's claim to the haul. The ship, called the Nuestra Senora de las Mercedes, was sunk by British warships in the Atlantic in 1804 while sailing back from South America with more than 200 people on board. Odyssey created an international splash in May 2007 when it announced that it had recovered more than 500,000 silver coins and other artifacts from the wreck and flew the treasure back to Tampa. Spain went to the U.S. District Court in Tampa, where the company is based, claiming ownership. Odyssey disputed the Spanish government's ownership of the valuable cargo. James Goold, a Washington attorney who represented the Spanish government in court, called the appeals court decision "a complete and much-deserved victory." "The court recognized that stripping the sunken Spanish ship of coins to sell to collectors is no more appropriate than to do that to the USS Arizona in Pearl Harbor," Goold said. "We are pleased and gratified that the court recognized U.S. obligations under international law, just as Spain respects the sanctity of sunken U.S. Navy ships." A federal judge sided with Spain in the first round of the tug-of-war in June 2009, accepting the Spanish government's argument that it never surrendered ownership of the ship and its contents. Attorneys argued the case before the 11th Circuit panel in May. Odyssey had argued that the wreck was never positively identified as the Nuestra Senora de las Mercedes. And if it was that vessel, then the ship was on a commercial trade trip — not a sovereign mission — at the time it sank, meaning Spain would have no firm claim to the booty. International treaties generally hold that warships sunk in battle are protected from treasure seekers.