Fighters for the Daesh terrorist group are targeting children in Mosul to prevent civilians from fleeing the city as Iraqi forces push into the last stronghold held in Iraq by the militants there, the United Nations said yesterday.

The U.N. children's agency said it has documented a number of cases in which Daesh fighters killed the children of families trying to escape from neighborhoods controlled by the militants.

"They are using children as a weapon of war to prevent people from fleeing," said UNICEF's Iraq representative, Peter Hawkins. "This just highlights how indiscriminate and catastrophic this war is."

Iraqi troops are slowly clearing the last pockets of Daesh fighters from Mosul's old city in an operation launched earlier this week. But an estimated 100,000 civilians packed into the dense terrain have slowed progress.

UNICEF said 1,075 Iraqi children have been killed and 1,130 wounded since Daesh militants overran nearly a third of Iraq in 2014. In the past six months alone, violence in Iraq has killed 152 children and injured 255, it said. In addition, the agency said, more than 1 million children have had their educations put on hold by either militant rule or displacement. There have been 138 attacks on schools and 58 on hospitals; more than 3 million children do not attend school on a regular basis while 1.2 million children are out of school and, one in every four children comes from a poor household, UNICEF said.

Children have also been forced to take part in violence. UNICEF said at least 231 children under the age of 18 were recruited by Daesh and other armed groups. "The country's future security and economic strength is determined by what is happening to its children today," Hawkins said.

The agency said more than 5 million children are in need of urgent humanitarian assistance. "Across Iraq, children continue to witness sheer horror and unimaginable violence," Hawkins said. "They have been killed, injured, abducted and forced to shoot and kill in one of the most brutal wars in recent history."

Daesh destroyed Mosul's al-Nuri mosque and its iconic leaning minaret known as al-Hadba when fighters detonated explosives inside the structures on Wednesday night, Iraq's Ministry of Defense said. Iraqi Prime Minister Haider al-Abadi tweeted that the destruction was an admission by the militants that they are losing the fight for Iraq's second-largest city. The mosque, which is also known as Mosul's Great Mosque, is where Daesh leader Abu Bakr al-Baghdadi declared a so-called Islamic caliphate in 2014 shortly after Mosul was overrun by the militants. The minaret that leaned like Italy's Tower of Pisa had stood for more than 840 years.

Daesh fighters initially attempted to destroy the minaret in July 2014. The militants said the structure contradicted their fundamentalist interpretation of Islam, but Mosul residents converged on the area and formed a human chain to protect it. Daesh has demolished dozens of historic and archaeological sites in and around Mosul, saying they promoted idolatry.

The fight to retake Mosul is estimated to have killed and injured thousands of civilians. The Iraqi government says more than 850,000 people have been forced from their homes by the operation, which was launched in October. On the city's west, entire blocks have been flattened by clashes, airstrikes and artillery fire.