A Thai national was arrested at the Calcutta airport early on Sunday for carrying an unlicensed gun.

Tanasupt Thummasaroch, 38, who claimed to be an electrical engineer working for merchant navy, was carrying the unassembled parts of the 4.5-mm bore pistol in his luggage.

“He said the gun was an air pistol used in the sports arena but could not produce any documents. Besides, the authorities were in the dark about the weapon,” said an officer at the Netaji Subhas Chandra Bose International Airport police station. “The gun will be sent to an expert to ascertain whether it is really meant for sporting activities.”

Thummasaroch, who had arrived at Calcutta port on Saturday, reached the airport around midnight to catch a Thai Airways flight back home.

He deposited a red bag at the X-ray counter. The Air India official manning the counter — the national carrier looks after ground handling in the international terminal — found “some metal pieces” in the bag and asked Thummasaroch to open it.

After assembling the pieces, the official realised they were parts of a 4.5-mm pistol. “Thummasaroch claimed he had bought the gun in France for euro 2 but could not produce any papers,” the police officer said.

The flier was detained and a second search of the bag revealed four small cylinders containing composed carbon dioxide gas. Thummasaroch allegedly failed to explain why he was carrying the gas.

The airline then contacted CISF officers, who handed over the Thai national to the police. Thummasaroch told officers that he had been sailing for a long time and had visited France once.

He has been remanded in judicial custody till October 17.