A suicide bomber blew himself up Friday among civilians fleeing the Old City of Mosul, where increasingly desperate jihadists are mounting a bloody last stand.

The carnage came just over a day after the Islamic State group blew up the mosque where its leader Abu Bakr al-Baghdadi proclaimed himself "caliph" three years ago, as well as its iconic ancient leaning minaret.

According to a major and medic in the Iraqi army, a bomber who had blended in with fleeing civilians killed at least 12 people in the Mashahda area of the Old City.

"We received 12 people killed and more than 20 wounded in our field hospital, including women and children," Ahmed Hashem told AFP from a nearby field hospital.

According to Abdelghani al-Assadi, a top commander in the Counter-Terrorism Service that has spearheaded the fighting against IS since 2014, around 8,000 people have managed to flee the Old City since an assault was launched on June 18.

Around 100,000 more are believed to remain trapped by the jihadists, who have made human shields a key element in their defence of old Mosul, their last redoubt in Iraq's second city.

The security forces have been wary of Iraqi IS members attempting to flee the Old City death trap by blending in with the population, while the Chechen, French and other foreign jihadists stay behind to mount a suicidal last stand.

Omar, his black and grey shirt covered in blood, was one of the more than 20 wounded being treated at the army field hospital following the blast.

"When the security forces started approaching our area, we ran to meet them," the young man said, nursing a head wound.

- Weeks till victory? -

"A man popped up and shouted 'Allahu Akbar' (God is greatest) before blowing himself up," said Omar. He said his mother and brother were killed while his sister-in-law and two children were missing.

Those civilians left in the Old City's IS-held areas face multiple dangers.

Those who attempt to flee have to cross some of the most active front lines in three years of war against IS and risk being executed by the jihadists if they fail to escape.

Those who choose to stay or have no choice have been essentially besieged for months with scant drinking water and food in areas that are being hit by air strikes and artillery on a daily basis.

More than 800,000 people have been forced to flee their homes since tens of thousands of Iraqi forces on October 17 launched a massive operation to wrest back the country's second city from IS.

The population density of the Old City of Mosul and its narrow streets make the latest push a very dangerous and complicated operation.

On Wednesday evening, the Nuri mosque in which Baghdadi gave his first sermon as IS leader in July 2014 as well as the nearby 12th-century "Hadba" (hunchback) minaret were blown up.

Officials in Iraq and its partner nations argued this act was one of desperation and an admission of defeat.

IS blamed a US air strike and released a video late Thursday showing the levelled monuments, where Iraqi forces have not yet arrived.

"Almost 50 percent of the Old City has been retaken. We don't control Nuri but we will within 48 hours," a senior officer in CTS said.

Assadi remained cautious when asked how much longer the battle might last and said the hardest might be yet to come.

"I cannot give you an exact estimate... but it will take weeks," he said.

An Iraqi intelligence officer speaking on condition of anonymity on the edges of the Old City said suicide bombers disguised as members of the security forces were one of the biggest threats as the operation progressed.

He said many of the hundreds of IS fighters thought to have been hunkering down in the Old City last week have already been killed.

"There could be no more than 200 left now," he said, as clouds of smoke from strikes and mortar shelling billowed into the sky behind him.

"All the others were killed, except 15 or 20 who were arrested as they tried to flee posing as displaced people," he said.

Source: AFP