#MosulOp: Iraqi forces discover 'headless bodies' in mass graves
The grave was found at the agricultural college in Hamam al-Alil area, about 14 kilometres [8 miles] from the southern outskirts of Mosul, the last IS-held Iraqi city.
The pit was found to be containing dozens of decapitated skeletal remains buried in shallow graves among garbage.
"Iraqi forces found... 100 bodies of citizens with their heads cut off" at the college, and that specialised teams would investigate, the Joint Operations Command [JOC] said.
Iraqi officials have previously estimated the number of victims in mass graves before they have been excavated and counted.
The militant group overran large areas north and west of Baghdad in 2014, declaring a cross-border "caliphate" that also included territory in Syria.
Its rule has been marked by repeated atrocities including mass beheadings and other executions that it has documented in photos and videos lauding the violence that its supporters share online.
Iraqi forces have since regained much of the territory that IS seized, and have uncovered a series of mass graves and massacre sites as they have pushed the militants back.
Iraqi forces are now fighting to retake Mosul from IS, and Hamam al-Alil was one of the last major obstacles between them and the southern outskirts of the city.