Two of the ten cases registered by Assam police in the wake of the proscribed Ulfa (I)’s disclosure of having planted bombs at 24 locations across the state on Independence Day will be handed over to the National Investigation Agency (NIA).

Assam police chief G.P. Singh revealed on Tuesday that they had moved the state government to hand over the two cases to the NIA, the country’s specialised central counter-terrorism law enforcement agency, given the complex nature of the overall case.

The two cases were registered in Guwahati and Lakhimpur.

Singh said four persons have been arrested in connection with the planting of bombs in Sivasagar, adding the police would take those involved to task as per law and were committed to maintaining order.

The move to seek NIA help follows the setting up of special investigation teams in the districts from where the "bomb-like devices" were recovered and the announcement of a financial award of ₹5 lakh to get "credible information" on the persons who made, transported and planted the bombs.

The August 15 development suggests the Ulfa (I) is far from being a spent force as claimed by certain sections, and the outfit could exploit the turmoil in neighbouring Myanmar and Bangladesh to regroup, sources said.

The number of districts from where bomb-like devices were recovered is five, including Kamrup (Metro) district, which covers Guwahati city.

The disclosure by the Ulfa (I), the only outfit from the state to be out of the peace process, through a media statement on Thursday sent the administration and the public into a tizzy resulting in an intensive search operation for the bombs and for people responsible for planting the explosives.

The disclosure saw the state government face flak for the apparent security lapses which were used by the outfit to plant the bombs or bomb-like objects.

The bombs were timed to go off between 6am and noon on Independence Day but did not because of the low voltage of the batteries the bomb-like devices were connected to.

Intensified surveillance in the wake of the Ulfa (I) bomb threat has seen the police arrest a suspected cadre of the outfit, Pawan Darji, in Guwahati on Monday night.

He is accused of extorting money following the situation arising out of the outfit’s disclosure of planting bombs at 24 locations despite tight security in the run-up to Independence Day.

GP Singh further said that the bomb threat mail received by the Guwahati mall — City Centre — on Monday was a hoax as nothing was recovered following a thorough search after evacuating visitors and staff of the mall.

The mall authorities had put up a sign saying the building has to be shut down for two hours because of technical reasons while asking visitors and staff to clear the eight-storey building.

After a search of the building, the police said the mall authorities had received a mail from an unknown organisation, named KNR, about a bomb being planted in the mall but it turned out to be a hoax mail as nothing was recovered during the search.