Jonathan Blair, Associated Press
Ground-crew members of Odyssey Marine Exploration unload more than 17 tons of silver coins May 16, 2007, at an undisclosed location. The coins were found in a shipwreck in the Atlantic Ocean.

TAMPA, Fla. — Peru's government wants to know if 17 tons of silver coins recovered from a shipwreck in the Atlantic Ocean last year were made there, complicating the legal quest to determine who rightfully owns the multimillion-dollar treasure.

Peru filed a claim Tuesday in U.S. District Court in Tampa to determine where the coins originated, entering the fray over the $500 million loot found on a sunken ship by Tampa-based Odyssey Marine Exploration. Odyssey has been fighting the Spanish government for ownership of the ship and its contents.

Peruvian consumer rights advocates contend the coins were made with Peruvian metals and minted in Lima. When Nuestra Senora de las Mercedes y las Animas sank west of Portugal with more than 200 people on board in 1804, Peru was still a Spanish colony.

"Probably every colonial Spanish shipwreck that has ever been discovered has had coins that originated in Peru," Greg Stemm, Odyssey Marine Exploration's chief executive officer, wrote in an e-mail. "So it will be interesting to see how successful they are in getting other governments and shipwreck explorers to recognize their interest."

Peru's claim states that it is entitled to any property that originated there and was produced by its people. An official at the Peruvian embassy in Washington, D.C., declined to comment.

Charles M. Davis, a maritime lawyer and author in Washington, said he couldn't recall another salvage case involving a former colony. Because technology such as submersible robots used by deep-sea explorers to find treasure is still new, he said, "There's a surprising dearth of law on high seas salvage." The case has been closely watched because similar disputes could become more common.

Odyssey officials have argued they're entitled to the booty because they found it. Spain has argued it technically never abandoned any of its ships lost at sea. Officials there want any artifacts returned because of their historical and cultural significance, and some in Spain have portrayed Odyssey as 21st-century pirates.

A message left with an attorney representing Spain was not immediately returned Wednesday afternoon.

Peru is not the only country seeking ownership of its antiquities. Greece is trying to reclaim illegally exported antiquities from museums and art dealers as part of an effort to recover the Parthenon sculptures from the British Museum in London.