The arrest was confirmed yesterday (June 24) by police spokesman Pol Lt Gen Prawut Thawornsiri.
Pol Lt Gen Prawut said police in Thailand were examining reports about Pol Lt Gen Kamronwit's arrest to find out why he had the gun with him, whether the weapon had gone through security procedures in Thailand and how.
Police would then contact him to see if he needed help.
Initial reports said Pol Lt Gen Kamronwit went to Japan last Thursday (June 18) on Thai Airways Flight TG 640 which left Suvarnabhumi airport at 9.50pm.
He was found with a gun in his possession at Narita airport as he was about to board a 5pm flight to return to Thailand on Monday (June 22).
The type of gun was not reported, nor how it was found.
Pol Lt Gen Kamronwit admitted to owning the gun and showed his identity card and documents for the weapon.
Airports of Thailand Plc deputy director Kanputt Mungklusiri said officials have examined footage from a CCTV camera at a gate at Suvarnabhumi which the former city police chief passed through.
The weapon seemed not to be detected by screening procedures, he added. However, Pol Lt Gen Kamronwit might have used a VIP gate at the airport where security screening is not required, a source said.
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