HAILAKANDI, July 17 - A fear psychosis has gripped the people of the three districts of Barak Valley due to the spurt in the activities of Pakistan's Inter-Services Intelligence (ISI) in the area. People fear that the ISI agents may strike in the valley in any time. The district administration of Karimganj has tightened vigil along the border with a view to stop the entry of ISI-supported infiltrators from Bangladesh. The district administration was alerted by intelligence agencies that ISI agents and supporters were active in the area. Infiltrators from Bangladesh have been changing the demographic set-up of the entire Barak Valley. Rickshaw-pullers from Bangladesh come to Karimganj every morning and return in the evening after earning their livelihood. The administration is allegedly giving shelter to these infiltrators at the indirect behest of political leaders as the latter see them as a votebank.