The voice of Abdulkareem, 43, a former construction worker trapped inside the fast-shrinking Isis enclave in Mosul, trembles with fear as he describes the battle raging around him. He knows that it would be dangerous to try to escape, but it may be even more risky to stay where he is. He told The Independent in a phone interview: “I cannot speak more loudly because they [Isis] will shoot me if they catch me talking on the phone.”

Abdulkareem lives in the Dachat Barga neighbourhood near the al-Maydan district which is being heavily fought over as the Iraqi security forces pin Isis fighters, who may number only 300 combatants, in a small part of the Old City of Mosul with their backs to the Tigris River. “It is a small area, but it is like Stalingrad in that the buildings wrecked by bombs and shells provide good defensive positions,” says one observer, who wished to remain anonymous.

Abdulkareem can hear the sounds of fighting all around him in Dachat Barga, but he dare not go out and see exactly what is happening. “We can hear the roar of the bombing and the mortar fire,” he says. “But we don’t know whether it is the Iraqi army, the coalition airstrikes or Daesh [Isis].” A week ago, his sister and her husband were injured. A mortar shell hit their house, though nobody knew who fired it. He heard later that they were safe in the al-Farouq neighbourhood which had been overrun by Iraqi forces.

The assault on Mosul by the Iraqi government started on 17 October last year and has now been going on for 262 days. The investment of the Old City, with its close packed houses and narrow alleyways, has been going on for a much shorter time, but many of its inhabitants have run out of food. “We have only wheat grain to cook and eat,” says Abdulkareem. “We buy 10 litres of water for 15,000 Iraqi dinars (about £10).” The water comes from deep wells dug since Isis captured Mosul three years ago, but petrol is needed to work the pump bringing up the water and this is often unavailable.

Nobody knows how many people are dying in the last stages of the siege as the last resistance of Isis is extinguished. Iraqi military commanders prematurely announce the capture of a neighbourhood long before it is secured. Hasan, who is working with a medical team searching the rubble for bodies, says that people are flooding out of the ruins when they think it safe to do so. “We are receiving hundreds of civilians from Al-Farouq and Al-Maydan and the other surrounding areas of the Old City,” he says. “Most of the victims are women and children. Yesterday three women dressed in black were wearing explosive belts. They blew themselves up and killed dozens of civilians and wounded many others.”

ORDER IT NOW

Some people have kept the dead bodies of their children and family members in their houses, because they will be shot if they try to go outside to bury them. “A woman was trying to flee with her three children,” says Hasan. “The children were shot and the Isis militants let the woman go. This happened two days ago in a small neighbourhood in the old city called Dachat Barga.”

The level of destruction in Mosul is worse than in any previous battle in Iraq, say senior UN officials. Some 900,000 people have fled the city and over a third of them are in camps. Lise Grande, the UN coordinator for humanitarian affairs in Iraq, is quoted as saying that “the level of damage is far higher than we expected”. Six districts, including most of the ancient Old City, have been totally destroyed while all the others have been damaged to a greater or lesser degree. Basic repairs to water, electricity and health care facilities will be costly, far greater than the UN had predicted. There are no precise figures for civilian casualties since the start of the siege, but the UN says there have been 15,000 trauma injuries sent for treatment.

People from Mosul who flee say they were confined to their houses by Isis who said they would be shot if they opened their door and set foot in the street. This makes the decision to escape particularly fraught, worsened by a fear that government forces suspect that groups escaping include Isis fighters and suicide bombers in disguise. Displaced people try to establish their credentials as opponents of Isis by denouncing each other as Isis “sleepers”.

The dilemmas facing people within the last Isis strongholds in Mosul are explained by Abu Mohammed, 53, who last week fled the Old City with a group of civilians. Isis had, in fact, retreated from their neighbourhood, but they were not sure of this. The decision that they must all flee was taken by “a man whom the people of our neighbourhood all respect. He was rich and helped people a lot until he had become bankrupt. This man asked us to move out of our houses and rush towards the Iraqi army.”

When they reached Iraqi forces, they told them “about some Daesh men with us. I know a teenager who was with our group. He was later arrested and turned out to be Daesh. He was Iraqi but not from Mosul.” Abu Mohammed says that they suspected the teenager because he was looking healthy and well-fed and “not suffering from starvation like the other civilians”.

Iraqi government forces on the ground have never believed the propaganda line that Isis had no popular support among the Sunni Arab population of Mosul. They suspect that many refugees come from the families of Isis fighters or at least supported them. A UN aid worker said that she had “never seen such terrified people as a group of young men of military age just before they were vetted by the Iraqi forces as possible Isis fighters”.