The stones throw light on life two million years ago
The team behind the find say it shows that our pre-human ancestors had more sophisticated technical skills than was previously thought.
The researchers say the tools are from a time when man's ancestors were not thought to have had the mental or physical ability to fashion them.
The Nature report says the tools were found with bones of fish and mammals and had probably been used to cut up meat.
Egg shells were also found at the site, indicating that the inhabitants of the region had a varied diet.
The tool factory could date back to small ape-like pre-humans from before the development of the Homo evolutionary group.
Helene Roche, an archaeologist at the University of Paris, said: "They were more elaborate and sophisticated than what we had seen previously or thought possible for stone tools of this age."
Piecing together the past
The tools, found in northern Kenya's Rift Valley, were sharp flakes methodically chipped from a single rock.
Archaeologists pieced together more than 2,000 flakes found at the site to produce about 60 reconstructions of the original stones.
In reporting their finding, the team said two things demonstrate the skill of the early toolmakers:
Craig Feibel, a geologist on the team, said: "It's not like they were just randomly whacking away and knocking off whatever happens to come off."
Homo habilis, a species of pre-humans that lived about two million years ago, may have been the tool maker, it is thought.