Songkhla: Police have detained a suspect in relation to a bomb blast which derailed a freight train in this southern province on Saturday.
The suspect was spotted near the blast site shortly before the bomb exploded, police said.
Authorities are inspecting the site of the explosion, which has been cordoned off for security reasons.
They are also reviewing surveillance camera footage in the area to find clues as to how the suspect managed to plant the bomb on the tracks.
According to intelligence reports, the incident was linked to insurgents active in the deep South.
The security officials believe the attack was a retaliation against the authorities' treatment of insurgents in the area. One of them, Abdul Sorem, 32, died in an extrajudicial killing in Thepha district of Songkhla on Oct 25.
Authorities also are keeping an eye out for another suspect who they believed had surveyed the tracks between Hat Yai station in Songkhla and Padang Besar station in Malaysia.
The bombing forced the State Railway of Thailand to provide bus transfers for passengers booked to travel on express trains between Hat Yai and Padang Besar stations.
Other services are being diverted around the bombed track.