As many as 450,000 civilians are trapped in Mosul's Old City, caught up in house-to-house fighting between ISIS terrorists and Iraqi government forces and cut off from aid, Reuters cited the International Committee of the Red Cross (ICRC) on Wednesday.
The Iraqi army says it is in the final stages of its campaign to oust the ISIS terrorists from their last major stronghold in Iraq, seven months after the US-backed operation to recapture the city began.
Patrick Hamilton, ICRC deputy director for the Middle East, said civilians were facing "very stark choices" as food and water run out.
"This population is not only exposed to the immediate dangers of the conflict itself and being either targeted or hit as collateral damage, but is also facing the effects of just no longer really having much access to the basic essentials that they need to live," Hamilton said after a trip to Iraq.
Thousands have fled every day since the US-backed forces opened up a new front last week in the northwestern corner of the city, which includes the historic Old City center, where the militants are besieged.
The ICRC said Iraqi authorities were already overwhelmed by the exodus of 600,000 people from the city, Iraq's second largest, since October. Another 100,000 to 200,000 could flee the final battle for the Old City, it said, citing UN figures.
The agency has deployed mobile surgical teams close to the frontline but has not been able to access the Old City.
"People don't have enough to eat, don't have water," Hamilton said. "Babies, elderly and so on of course they are very vulnerable and may already be dying."
Hamilton said the battle for Mosul had been a "very long, attritional fight". The final phase was expected to be the most difficult in a densely populated ancient city with narrow alleyways, he said.