Two puppies were seized and handed over to RSPCA.
Officers from Atherstone's Safer Neighbour Team visited the Furnace End Car boot sale in Nuneaton Rd near Ansley.
They had received reports of puppies being sold from the back of a van.
Two puppies were found and seized, being given to the RSPCA.
Enquiries are ongoing.
The post on the Atherstone & Coleshill Police Facebook page ended with a warning for prospective dog buyers:
"Please do not buy any animals from the rear of vehicles. Go directly through a breeder or rescue shelter. If you witness any suspicious circumstances, please call 101."
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