Officials identified the youth as Raoof Ahmed, a resident of Bhatkal in north Karnataka.
Security agencies have been keeping a strict vigil after his name cropped up during internet chats with members of the Islamic State of Iraq and Syria (ISIS), which is being monitored by sleuths to look for possible followers of the terror group, active in parts of Syria and Iraq.
They said Ahmed was detained as the Union Home Ministry had issued a Look Out Circular against him sometime back.