Initial investigation found no link between Thai five students detained in Pakistan and either the insurgency in the far South or the Islamic State of Iraq and Syria.
Deputy Government Spokesman Maj General Sansern Kaewkamnerd said the motives to smuggle the handgun out of Pakistan would be further probed.
Five Thai religious students have been detained after Lahore airport staff found a handgun and munitions in their luggage while they were waiting to board a flight to Thailand.
X-ray images of the luggage reportedly showed a handgun dissembled and its parts kept in the luggage of the five students before being unloaded in Thai aircraft TG346 heading for Bangkok, at 10.40pm local departure time.
An adviser to Defence Minister Prawit Wongsuwan, Panitan Wattanayagorn, said the Thai intelligence service was aware of the incident.
He said one of the detained students, who hails from Pattani, reportedly told Lahore airport security staff that a stranger convinced them to carry a container that had the handgun's parts - a claim Panitan said needed to be further scrutinised.
Panitan said there were no known links between the five students and the insurgency in southern Thailand or the Islamic State of Iraq and Syria.
Army commander Udomdej Sitabutr said that Prime Minister General Prayut Chan-o-cha had learned of the arrest and ordered the Foreign Ministry to pursue the case to help out the five students.
All students are male adults but under 20 years of age, hence publication of their names in the media is not allowed.
No links to South discovered
They were reportedly seeking a post-high-school diploma in Islamic studies.
The students came from the provinces of Pattani, Trang, Chachoengsao, Songkhla and Krabi.
The home of the Krabi student has been searched by the police's local Special Branch office.
His parents reportedly told police that their son studied in Pakistan for two years and was about to return home to postpone his Army conscription draw and had been in constant contact with them.
His mother told reporters that she believed he had no links to the insurgency and he was sent |to study in Pakistan as it was affordable for the family, since they paid only Bt4,000 a month for food and room while the tuition and school supplies were all free.
Foreign Ministry spokesman Sek Wannamethee said the Thai side was coordinating with Pakistani authorities shortly after the incident occurred, and that a request to visit the students had been made, but a response was yet to be received.