The officers from a special anti-crime squad were arrested on Tuesday and detained as part of an investigation into organised theft, extortion, violence and drugs.
They are suspected of having stolen drugs and cash from dealers and taking cigarettes from illicit sellers.
The source said 500 grams (18 ounces) of hashish and money had been found. Radio station RTL Thursday reported that the stash included jewellery.
The arrests were the latest in a series of incidents bringing French law enforcement under scrutiny.
In September, Michel Neyret — the deputy police chief of Lyon who was hailed for cutting drug crime and jewellery heists — was arrested after being accused of accepting gifts and favours from members of the city's underworld.