The militant hurled a grenade on the personnel of the 19 Dogra Regiment troops at Khourdanga, injuring two of them, following which the troops retaliated.
The militant, identified later as Niyor Asom alias Bubul Ali, was killed in the encounter, they said.
A pistol, three magazines and a large quantity of ammunition were recovered from the slain ultra, officials said.
Ahead of the Feb 14 assembly elections in Tripura, two jawans of paramilitary Tripura State Rifles (TSR) were killed and two others injured today at Tankharai, a remote tribal hamlet in Dhalai district, about 150 km from here, police said.
A TSR jawan, identified as Binoy Debbarma, following an altercation with his colleagues at the Tankharai camp opened fire killing two of his colleagues and severely injuring two others. The incident occurred at about 4.30 pm.