Argentina has said it will return more than 4,000 archaeological artefacts to Ecuador and Peru.
President Cristina Fernandez de Kirchner said the pieces had been stolen and should be returned to their rightful owners.
"We are doing something unusual, really special," she said during a ceremony at the National Museum of Fine Art in Buenos Aires.
Ms Fernandez urged other countries to follow the example.
"It is an honour and a pleasure to restore the cultural wealth of countries such as Ecuador and Peru in a world where such wealth has so often been taken away," she said.
"One can see in the great museums of the world pieces from Greece, Syria, Egypt, Asia and even Latin America, and which have not been returned."
The announcement was made during a ceremony in Buenos Aires, in the presence of the Ecuadorean and Peruvian ambassadors.
Ms Fernandez said Argentina was the first South American nation to make such gesture.
But she did not specify when the artefacts would be returned.
Last year, Yale University in the United States returned dozens of Inca artefacts.
The university had reached a deal in 2011 to return thousands of items after a long dispute.
The artefacts had been taken from the Incan 15th Century citadel of Machu Picchu by American explorer Hiram Bingham in 1912.