The recovered IED was planted on a North Bengal bound bus by suspected ULFA militants.

A security source informed that the double-detonator enhances the precision of the bomb besides making defusing it extremely risky. In case of such an IED, if one detonator fails to explode, the other dormant detonator automatically turns active.

The recovery of the improved IEDs has thrown up a fresh challenge before security forces fighting ULFA insurgents in Assam. A police source informed that the banned ULFA would desperately try to strike terror in big way in the run up to Independence Day to avenge the recent split in its ranks.

Two crack companies of the ULFA, broke ranks to mobilize people's opinion for direct talks between the ULFA top brass and the government for finding a permanent solution to the problem.

Meanwhile, the Assam government has instructed the forces to gear up vigil on all the vital installations including the oil industry and railway properties, given that the militants in Assam have the track record of blowing up railway and oil properties in the state.

There are intelligence inputs about explosives experts from fundamentalists groups, sneaking into the state to strike terror.