A close associate of ULFA chief Paresh Barua was killed in an encounter with security forces in Assam's Kokrajhar district on Saturday,police said. Acting on a tip-off,a joint team of police and army personnel cordoned off a house in Kalipukhuri area where Prannoy Roy alias Pranab,responsible for several bomb blasts and extortion in Lower Assam districts,was hiding. When the militant opened fire,the security forces retaliated killing him on the spot,they said. A 9 mm pistol,a Chinese grenade,three electronic detonators,several rounds of ammunition,a satellite phone and three mobile phones were seized. Roy was the second-in-command of the outfit's '709 Battalion'. He had joined the outfit in 1996 and was trained in Bhutan. Police suspect that the militant was planning to carry out attacks in the run-up to the Durga Puja festivities.