The bags were found to contain five ploughshare tortoises and 325 radiated tortoises, all of them alive. Officials said both species are considered critically endangered by the International Union for Conservation of Nature.
The boxes were falsely labeled "stones" and bore a fake address for the intended recipient, investigators said.
"We are very serious about tackling wildlife crime involving Malaysia, especially through KLIA," Customs Deputy Director for Enforcement and Compliance Abdull Wahid Sulong said at a Monday news conference.
Traffic, the wildlife trade monitoring network, hailed Sunday's discovery, as well as other recent wildlife-related seizures at the Kuala Lumpur airport.
"The string of seizures certainly shows that Malaysian Customs means business and Traffic is glad to see this action against organized criminal wildlife trafficking," said Kanitha Krishnasamy, senior program manager for Traffic in Southeast Asia.
No arrests were made Sunday. The investigation was ongoing.
