Odyssey Marine Exploration and Spain have been arguing over the treasure since the trove was found last year at an undisclosed location in the Atlantic Ocean.

U.S. District Judge Steven Merryday ruled on Thursday that Odyssey's lawsuit claiming rights to the treasure could go forward provided the company promptly identifies the wreck for Spain, or gives its "best available hypothesis" of the identity.

At a court hearing on Wednesday, the company's lawyers said Odyssey did not know for certain the name or nationality of the wreck, from which the company recovered some 17 tonnes of silver coins and gold.

"We want to know the identity of this vessel, and what this ruling is saying is 'It's not an answer to say we haven't decided for sure,'" said lawyer James Goold, who is representing Spain.

Merryday ruled that parts of Odyssey's lawsuit could go forward through the courts, including claims for possession and ownership of the wreck and the artifacts.

But he sided with Spain on several other elements of the suit, dismissing Odyssey's claims for monetary damages from Spain and a request for an injunction to "secure the integrity of the recovery operation against interference from a third party."

The two sides have been at odds since Odyssey announced last May that it had found half a million silver coins and other artifacts. It said the wreck, which it code-named "Black Swan," was discovered in the Atlantic Ocean outside any country's territorial waters.

The dispute turned ugly when Spanish warships twice intercepted the company's treasure hunting ships after they left the British territory of Gibraltar and escorted them to Spanish ports.