Authorities are investigating whether some 150 farms in northern Germany made false claims about the quality of their eggs.
Prosecutors in the city of Oldenburg suspect the farms sold the eggs as organic or free-range when in fact they didn't meet strict labeling requirements.
A spokesman for the country's consumer protection ministry said Monday that if suspicions are confirmed it would constitute "large-scale fraud."
Holger Eichele told reporters in Berlin that the investigation, which centers on whether hens were fed inappropriate feed and whether too many animals were kept in each pen, would soon be completed.
The probe comes amid heightened sensitivity in Germany about food quality, after a Europe-wide trade in horse meat labeled as beef was uncovered last month.