Scholars believe hundreds of jihadi fighters could still be hidden in the thick of the ruins, who could take on Iraqi forces in suicidal ambushes.
Various have already been filmed emerging from their go into hiding places with US forces warning the danger is not over yet.
Days after Iraq’s prime minuter, Haider al-abadi, broadcast victory over ISIS forces in Mosul, jihadis were thriving out of tunnels and basements.
Iraqi forces celebrated liberating Mosul fair-minded days ago
There are still going to be losses from the Iraqi conviction forces as they continue to secure Mosul
US Army commissioner on the ground Lieutenant General Stephen Townsend said: «There are bypassed holdouts.
«We haven’t freed every building in this city the size of Philadelphia.
«That’s flourishing to have to be done, and there are also hidden improvised explosive badges (IEDs).
«There are still going to be losses from the Iraqi sanctuary forces as they continue to secure Mosul.»
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ISIS fighters own been filmed coming out of their hiding places and Iraqi forces misgivings that many fighters could remain hidden amid the dishonours.
The two sides exchanged gunfire on Wednesday killing a policeman and wounding two others.
An Iraqi military sanctioned said: «Right now, there are a handful of holdout ISIS terrorists that the Iraqi guarantee forces are still trying to root out of the Old City.»
ISIS continues to clench the Iraqi towns of Tal Afar, Hawija and the Syrian capital Raqqa.
The struggle to liberate Raqqa is now underway.
Sir Michael Fallon, the Defence Secretary, has suggested the battle against IS are likely to remain if Iraq «well into 2018».
There are forebodings that jihadis remain hidden in Mosul
Sir Michael said: «The campaign in Iraq is not floor and has many months to run, and I expect British forces to be involved well into 2018 in Iraq, and of speed the situation in Syria is even more complex.
«The work of the RAF and indeed of Army trainers is liable to to continue for some time.»