Border officers at Heathrow Airport have seized 50 crocodiles destined to be bred for their meat.
The illegal shipment of year-old juvenile saltwater crocodiles was found by staff in five boxes which had come from Malaysia.
They were destined for a farm in Cambridgeshire, where they were to be bred for their meat.
The animals , weighing around 40kgs, had not been packed in accordance with International Air Transport Association (IATA) regulations, invalidating their permit and making the importation illegal.
Each box only had room for four crocodiles but 10 foot-long reptiles had been packed into each one.
Grant Miller, head of the national Border Force Convention on International Trade in Endangered Species (CITES) at Heathrow, said: "It is just not acceptable for reptiles to be transported in this way.
"The crocodiles had started to fight each other during the flight as space was limited, so little attention had been paid to their welfare.
"We will seize anything that contravenes CITES regulations, so this should serve as a warning to those thinking about transporting wildlife in such conditions."
One crocodile has died since the discovery on April 27 and the remaining animals are being cared for before being re-homed.