▁min istry . ▁ ▁It ▁is ▁part ▁of ▁the ▁Government ▁of ▁India ▁located ▁in ▁the ▁South ▁Block ▁of ▁the ▁Secret ariat ▁Building . ▁ ▁History ▁During ▁the ▁ten ure ▁of ▁J aw ah ar l al ▁Ne h ru ▁as ▁Prime ▁Minister , ▁the ▁then ▁Prime ▁Minister ' s ▁Secret ariat ▁was ▁head ed ▁by ▁a ▁J oint ▁Secretary ▁until ▁his ▁death . ▁The ▁post ▁of ▁Princi pal ▁Secretary ▁to ▁Prime ▁Minister ▁was ▁created ▁during ▁the ▁ten ure ▁of ▁Ind ira ▁Gand hi ▁as ▁Prime ▁Minister . ▁The ▁Princi pal ▁Secretary ▁to ▁PM ▁is ▁the ▁head ▁of ▁the ▁Prime ▁Minister ' s ▁Office . ▁ ▁Function ▁The ▁P MO ▁provides ▁secret arial ▁assistance ▁to ▁the ▁Prime ▁Minister . ▁It ▁is ▁head ed ▁by ▁the ▁Princi pal ▁Secretary ▁to ▁the ▁Prime ▁Minister . ▁The ▁P MO ▁includes ▁the ▁anti - cor ruption ▁unit ▁and ▁the ▁public ▁wing ▁dealing ▁with ▁gr iev ances . ▁The ▁office ▁houses ▁the ▁Prime ▁Minister ▁and ▁few ▁selected ▁officers ▁of ▁Indian ▁Civil ▁Service ▁who ▁work ▁with ▁him ▁to ▁manage ▁and ▁coordinate ▁government ▁and ▁his ▁office . ▁The ▁Prime ▁Minister ▁through ▁his ▁office ▁coordinates ▁with ▁all ▁minister s ▁in ▁the ▁central ▁union ▁cabinet , ▁minister ▁of ▁independent ▁charges ▁and ▁govern ors ▁and ▁minister s ▁of ▁state ▁government . ▁The ▁P MO ▁is ▁located ▁at ▁the ▁South ▁Block ▁of ▁the ▁Secret ariat ▁Building . ▁ ▁The ▁subject - m atter ▁of ▁files ▁required ▁to ▁be ▁submitted ▁to ▁the ▁Prime ▁Minister ▁depends ▁on ▁whether ▁he ▁is ▁holding ▁direct ▁charge ▁of ▁the ▁Ministry ▁or