Peru is threatening to sue Yale University in America, for the return of ancient mummies, bones and ceramics, that were taken from Machu Picchu. The items were taken by an American explorer nearly a century ago. The president of Peru at the time, Augusto Leguia, gave the explorer permission to export the items temporarily for scientific study, but only for one year. That was extended by 18 months, and the items should have been returned in 1916. Peru's ambassador to Washington, Eduardo Ferrero has delivered a warning to the university. "Peru has notified [Yale's president] Richard Levin that a lawsuit is prepared if its rights to the archaeological pieces are not recognised," the Peruvian foreign ministry said in a statement. For more information, CLICK HERE.