According to intelligence reports, several groups of the outfit's anti-talk faction have sneaked into different parts of the start to carry out subversive activities and patrolling has been intensified to nab them, official sources said.
Security forces have carried out operations in Tinsukia, Sibsagar, Jorhat, Dhubri and other parts of the state and nabbed several militants who were planning to disrupt the Independence Day celebrations.
The anti-talk faction of the ULFA has called an Assam Bandh on August 15 and also joined several other militant outfits of the North East in calling a boycott and general strike on that day.
In a separate directive, the director general of civil aviation has asked airport authorities to tighten the vigil in and around all airports in the north eastern states.
The North East Frontier Railway has also decided to cancel and reschedule all night trains through Assam and Tripura until Aug 17 for security reasons.
A strict vigil was being maintained in and around all vital installations like oil pipelines, railway tracks, railway stations, bus terminus and others, sources added.