ULFA-Independent on Friday claimed responsibility for the blast near the gate of the army station in Assam's Jorhat district.
The 'mild blast' had occurred on Thursday night in a dustbin near the army gate in the town's Lichubari area, a defence spokesperson said.
Bomb experts have reached the spot and are ascertaining the explosives used in the blast, the spokesperson said.
There was no casualty or damage due to the blast, the third such incident near security establishments after Tinsukia and Sivasagar since November 22.
A massive search operation has been launched in the district and also in adjoining areas of Jorhat to nab the culprits.
Security has been tightened and patrolling intensified across Upper Assam districts.
ULFA-I, in the statement claiming responsibility for the blast, said the indigenous people had no cause to panic as the outfit is not against them but are carrying out the blasts due to the alleged efforts by the Director General of Police GP Singh to establish the outfit's demand as a "law and order problem and not a political issue".
The DGP or the Assam police is yet to respond to ULFA-I's allegation.
On Sunday, ULFA-I had in an e-mail "claimed responsibility for the two recent blasts in Tinsukia and Sivasagar" which was carried out in response to the 'arrogance' of Singh.
A grenade blast took place near an army camp at Dirak in Tinsukia on November 22 following which one person was arrested but police did not confirm the details of the sound of an explosion heard near a CRPF camp on December 9.
Following ULFA's earlier statement, the DGP had posted on 'X' that every personnel of Assam police, Army & CAPF take oath under the National Flag to protect the integrity and sovereignty of the country.
"We are committed to wipe out the remnants of terrorism that impedes growth of our state. And for that, if we have to sacrifice our life, we shall not hesitate, nor shall we waver from our determination to use full might of law against those who stand in path of our state's growth, progress and development," he said.
