American treasure hunting company, Odyssey has been told it must return to Spain a fortune in old coins recovered from a 19th-century Spanish warship.
A US court upheld an earlier ruling saying the trove, worth over 350 million euros, was the rightful property of Spain.
It is the latest twist in a complex dispute over the treasure involving Spain, Odyssey and Peru.
Odyssey is disputing the identification of the sunken frigate it found two years ago in what it says were international waters near the straits of Gibraltar.
Spain says it was the Nuestra Senora de las Mercedes which was carrying treasure back from Peru when it was sunk by the British in 1804.
Any shipwrecked military vessel, as opposed to a private commercial ship, according to the Spanish government, belongs to Spain.
But Odyssey, which specializes in the recovery of sunken treasure, says the coin haul came from a vessel it code named “Black Swan” and belongs to the company.
Odyssey is to be allowed to hold onto the treasure pending an appeal.