The Indian authorities detained a United Arab Emirates air force plane and its nine crew members on Sunday night for allegedly carrying arms without declaring the nature of the cargo.
The Hercules C-130 cargo carrier had stopped in Kolkata on way to China.
According to an airport official the plane was carrying arms to Xianyang in Shaanxi province in north-central China, but the UAE air force did not mention this while applying for landing and refuelling in Kolkata.
Central Industrial Security Force personnel sealed the aircraft and kept it under guard, while Intelligence Bureau and customs officials interrogated the crew at the airport.
On Monday, the crew members were interrogated for about four hours.