We have already managed to neutralise five of them although the threat perception is still very much there,' Satyaraj Hazarika, police chief of Dhemaji, said.

On Aug 15 2004, ULFA triggered a landmine in a college parade ground killing at least 20 people, 12 of them students, and wounding close to 100 more.

The ULFA has been fighting for an independent homeland since 1979.

Rebels in insurgency-hit Assam, the largest among the seven northeastern states, have for years been boycotting the Independence Day and Republic Day celebrations to protest the central government's rule over the vast region rich in oil, tea and timber.

The run-up to the events has always been violent, with ULFA striking vital installations including crude oil pipelines, trains, and road and rail bridges, besides targeting federal soldiers.