Following a tip-off, the military intelligence wing was keeping a strict vigil in the area, where Indian Air Force establishments are also functioning.
Intelligence wing officials nabbed Pasumatry and Bikaram Pasumatry, working in the factory belonging to a feed manufacturing unit at Sulur, 20 km from here, around midnight yesterday, police said.
Upan is suspected to be involved in an armed rebellion in Assam and had fled the state while Bikaram's brother is also said to be an active member of the separatist outfit, the sources said.
Senior police officials in the district were tight-lipped on the issue.