"We have seized 146 tortoises - 139 Radiated and 7 Angonoka species - which are endangered," Assistant Customs Commissioner Kiran Kumar Karlapu said.
He said the staff of Jet Airways brought a bag to AIU saying that some suspicious shell- like images had been noticed by security.
"The bag was said to belonged to a transit passenger who arrived from Madagascar and flew to Kathmandu leaving behind the bag," Karlapu said.
The AIU officers examined the bag and recovered the tortoises which were kept in a polythene cover.
"Since these were exotic species, they cannot be introduced into India and because of quarantine reasons, they were sent back to Madagascar," the officer added.