'The banned All Tripura Tiger Force (ATTF) might have hidden the arms and ammunition in the area as they could not enter the state by crossing the India-Bangladesh border due to the border fencing,' a BSF official told reporters.

At least 30 base and training camps of two Tripura insurgent outfits, the ATTF and the National Liberation Front of Tripura (NLFT), are in Bangladesh, which shares a 856-km border with Tripura.

Meanwhile, Das said three more tribal separatists of NLFT have surrendered to the security forces in northern Tripura Wednesday after fleeing from their bases in Bangladesh.