NEW DELHI: Over 6,600 posts reserved for SC/STs are lying vacant in the defence sector, the Lok Sabha was informed today.As per the data given by Defence Minister Manohar Parrikar in a written reply, there are 3,430 Schedule Caste backlog vacancy in the defence establishment and 3,182 Schedule Tribe posts in the defence establishment.The maximum vacancy was in the Department of Defence Production with 2,572 posts lying unoccupied (as of April 28, 2015). It was followed by the Navy (defence civilians) with 1,971 cases, he said.Parrikar said that the defence establishments have been instructed to put up their backlog vacancies of SC/ST on their respective websites.They have also been advised to form a Committee of Officers to monitor the progress of backlog vacancies meant for SC/ST, he said.De-reservation of SC vacancies is being discouraged and concerned defence establishments are advised to avoid de-reservation of SC/ST vacancies in accordance with the guidelines and provisions of DoPT.