RSPCA Animal Welfare Officer Steve Wickham said the clouded monitor lizard is a protected species in Thailand and can grow up to 5 feet long.
"Despite being zipped up in a suitcase for at least 24 hours, the monitor lizard appeared to be in good health," Wickham said. "I took the lizard to a specialist exotics center to be checked over by a vet and cared for, where it ate almost straight away. The long journey must have made them very hungry!"
Wickham said the RSPCA is seeking permission from Thai officials to send the lizard to a zoo or wildlife sanctuary.
"Thankfully the lizard will now be cared for by experts," he said. "However, this is a timely reminder to people to always check your suitcase, clothes, towels and shoes properly when packing to return home from a trip abroad, as you never quite know what surprising souvenir you might bring home with you!"