A collection of supposed pre-Hispanic artifacts seized from a controversial private antiquities dealer in Germany contains many pieces that are fake, Mexico's government archaeology agency said Thursday.

The National Institute of Anthropology and History said most of the larger, impressive pieces seized by German authorities from Costa Rican dealer Leonardo Patterson are modern copies of ancient artifacts.

The institute said experts who examined the collection of 1,029 sculptures, pots and figurines had determined 252 are fakes.