A labourer was killed and two others injured by suspected NDFB militants at Dadgiri near Indo-Bhutan border in Chirang district, IGP (Law and Order) L R Bishnoi told PTI.
The labourers, hailing from Malda in West Bengal, had gone to Bhutan to work and were attacked by a group of militants while they were returning.
In another incident, an NSCN(IM) ultra was killed in an encounter during an operation by the police and army at Nimnagarh in Sibsagar district along Assam-Nagaland border.
Meanwhile, security personnel recovered a powerful bomb, weighing over two kgs, from under a bridge on NH-31 at Padmabil under Gosaigaon police station in Kokrajhar district.
Another IED, weighing more than two kilograms, was recovered by patrolling troops of the army's Punjab Regiment from Puthimari Nagaon village under Kamalpur police station of the district.
Security has been beefed up throughout the state following intelligence reports that ULFA's anti-talk faction, which has called a bandh on August 15, was planning to create disturbances in the run-up to the Independence Day.