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."
M1 closed northbound due to 'serious collison'
Plaque unveiled in Shepshed in memory of firefighter
Loughborough University-based Katarina Johnson-Thompson wins heptathlon bronze
The UK's only bonobo baby born at Twycross Zoo
University Hospitals of Leicester NHS Trust part of national investigation
Yellow warning for wind in Loughborough and Charnwood
Leicestershire team raise funds for a tranquil garden space for victims and survivors of sexual assault
New bigger Primark store opens in Loughborough
