CHENNAI: The Directorate of Revenue Intelligence busted a gold smuggling racket at Chennai airport on Sunday and seized gold biscuits worth Rs 9.5 crore hidden in a toilet on a flight from Dubai.

On its next leg the flight was to leave for Delhi, the possible destination of the gold, investigators said.

Four Sri Lankan nationals including two passengers from Dubai and their two accomplices who were going to board the plane to Delhi were taken into custody. In all there were 32 gold biscuits, each weighing 1kg on board the Air India flight that came from Dubai at 5.15am.

The smugglers ostensibly knew that the flight would go to Delhi, and they planted the gold in the toilet. The gold was concealed in two black camcorder bags inside the toilet next to the flight cockpit. DRI suspects a Dubai-based money laundering racket behind the smuggling.

The sleuths were acting on specific intelligence input they got about the smuggling. As soon as the two passengers got down at Chennai, DRI picked them up but didn't find anything in their baggage. "After arresting two passengers from Dubai, two others were taken into custody from the domestic terminal based on a tip-off. They were supposed to deliver the items at Delhi airport," said an official. A six-member DRI team inspected the aircraft and found two bags with 16 gold biscuits each in the toilet.

"The passengers from Dubai and the two passengers from Chennai to Delhi had booked their tickets in executive class. We are not ruling out the role of some airlines insiders in this smuggling bid," said the officer. A senior intelligence officer at the airport said they are looking at the role of airline staff who possibly told the smugglers that the same aircraft would fly to Delhi. "It is strange that no airline staff spotted two big bags inside the toilet next to flight captain's cabin," said the officer.

After witnessing a spurt in smuggling after the increase in import duty, revenue intelligence officers have tightened security measures at all Indian airports. To protect artisans and local gold traders from cheap gold imports, the government had raised the duty on gold to 15% from 10% last month.