KARAK - Different educational institutions of the district received threatening letters from some unknown quarters on Tuesday in which they have been asked to suspend the co-education or face dire consequences. According to details, some unknown persons, apparently militants, late Monday night pasted the letters, written in Pushto language, on the main gates of Government Post Graduate College and Polytechnic Institute Karak. The letters asked the administration of these institutions to end the co-education as there is no room in Islam for this system. The unknown writers of the letters also warned these institutions of dire consequences if they did not stop the co-education. According to sources, some unknown armed persons had barged into the Sentential Modal School, Chokara, last week and wrote warnings on the notice board of the school to suspend the co-education in the school or face the music and later they damaged school gate by opening fires. It was informed that the threatening letters were also sent to other private educational institutions situated in Chokara and other parts of the district.