LIMA, Peru —  Yale University is holding some 40,000 artifacts from the famed Inca citadel of Machu Picchu, a government official heading efforts to return the pieces told the state news agency Andina on Sunday.

Peru's government and Yale University reached an agreement last September to return 4,000 pieces — including mummies, ceramics and bones — that were taken a century ago from what has become one of the world's most famous archaeological sites.

The tally of 40,000 artifacts appeared in a report presented by archaeologists from the National Culture Institute to the Peruvian government earlier this month after taking an inventory at Yale, said Health Minister Hernan Garrido Lecca.

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Officials at the National Culture Institute and at Yale couldn't be reached Sunday for comment.

There were no indications of whether Peruvian officials previously knew about the additional 36,000 artifacts and no details of their historical significance.

Peru demanded the return of the collection in 2006, saying it never relinquished ownership when Yale scholar Hiram Bingham rediscovered Machu Picchu in 1911.

Yale responded with a proposal to split the collection.

Negotiations broke down, and Peru threatened a lawsuit.

Under last year's agreement, Yale and Peru will co-sponsor a travelling exhibition featuring Bingham's pieces and later a new museum in the Andean city of Cuzco, the ancient Inca capital.

The mountaintop, pre-Columbian ruins of Machu Picchu, which thrived in the mid-15th century, are Peru's top tourist attraction.