"Additionally no evidence exists that in any moment the sector in question could have been used as a stone-working site for the preparation of stone elements," it says.
The team, which notes that similar naturally occurring structures have been found in Machu Picchu, also found no construction foundation for the walls.
In January, experts interviewed by National Geographic News expressed doubts about the Paititi claim, stating that historical records put the probable location of the legendary city in another part of the Amazon.
Nonetheless, based on photographs of Manco Pata, some remained optimistic that the site would prove to be an important artifact of Inca or perhaps pre-Inca culture.
"The claims of it being such an extensive site seemed, as well, too good to be true," said Gregory Deyermenjian, a Massachusetts-based psychologist and explorer who has led expeditions to investigate the Paititi legend.
Days after Torres, the local mayor, announced the discovery of the find to the press, he met with INC officials, who in turn announced that Manco Pata would be declared a national heritage site.
As scientists headed to the site to determine its origins, rumors surfaced that Torres owned a local tourism company, and that villagers had known about Manco Pata for years.
Alex Lizaraso, an aide to Torres, confirmed in an interview that some locals had known of the site's existence for some years but kept its location quiet.
He also said Torres owned a small company that provides recreational space and a swimming pool to schoolchildren in a nearby town, but he did not expect to gain profits from tourism related to Manco Pata.
"Personally, I considered it an exaggeration to think the mayor would promote Manco Pata for personal ends," Lizaraso said.
Torres's office did not comment on the new INC report.
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