The attack on the army convoy in Goalpara was the handiwork of the anti-talk faction of ULFA, Assam Chief Minister Tarun Gogoi said.
"ULFA was involved in the blast... It was a sophisticated weapon they used and it was the handiwork of the ULFA," he told reporters.
"ULFA and other insurgent groups are tyring to create disturbance (in Assam). There is not doubt about it. The threat is there," he said, adding security forces deployed in the state are maintaining a constant vigil.
"Our security forces, including the army, are very confident that they will be able to catch the culprits."
Gogoi said he had spoken with the General Officer Commanding-in-Chief of Tezpur-based Four Corps about the attack in which militants had used an IED and destroyed an army vehicle about one and half kilometres from Naranarayan
Setu in Jogighopa. One soldier was killed and six others were injured in the attack.
The anti-talk faction of ULFA had claimed responsibility for the blast and that three army personnel were killed and nine others injured. Defence authorities had later denied it.
Asked if he would appoint a home minister in view of the recent violent incidents in the state, Gogoi said, "I will continue to hold the portfolio. And if I find somebody then I will make him (home minister). But it will be done as per my decision. It will not be according to the Delhi's wishes."
Gogoi currently holds the home portfolio and has come in for criticism to the failure to tackle last month's Bodo-immigrants conflict in lower Assam.