The source said a circular has been sent from Songkhla police head office to all stations, telling them to pay attention to traffic cones left on road corners. 
Police said many traffic cones have been stolen in the southern border provinces. 
Police at security checkpoints have been told to step up checks for fear insurgents might try to smuggle bombs into Songkhla. 
The move led to five men being arrested in Sadao district on Sunday night after they were found carrying guns, Sadao police chief Lt-Colonel Thavorn Polkla said.

Songkhla police boost security over traffic-cone bomb fears

The chief of Songkhla police has instructed all units in the southern border province to step up security over concerns insurgents will plant bombs in stolen traffic cones, a police source said.