UN’s children’s agency says children bearing the brunt of intensifying violence in ISIL-held areas of west Mosul.

Mosul’s children are bearing the brunt of the intensified fight between US-backed government forces and the Islamic State of Iraq and Syria (ISIL) group in the Iraqi city’s western half, the UN children’s agency warned on Monday.

Iraqi forces are continuing their operation to drive ISIL fighters from the remaining pockets of Mosul’s Old City, where narrow streets and a dense civilian population are complicating the fight.

Peter Hawkins, UNICEF representative in Iraq, estimated that 100,000 children are still in ISIL-held areas, living under extremely dangerous conditions.

Hawkins said the agency is receiving “alarming reports” of civilians being killed, including children, with some caught in the crossfire while trying to flee.

He did not give a specific number for killed children.

Hawkins called on the rival parties to “protect the children and keep them out of harm’s way at all times, in line with their obligations under humanitarian law.

“Children’s lives are on the line. Children are being killed, injured and used as human shields. Children are experiencing and witnessing terrible violence that no human being should ever witness,” he said in a statement.

“In some cases, they have been forced to participate in the fighting and violence.”

Backed by the US-led international coalition, Iraq launched a wide-scale military offensive last October to recapture Mosul and the surrounding areas, with various Iraqi military, police and paramilitary forces taking part in the operation.

The eastern half of Mosul, Iraq’s second largest city, was declared liberated in January, and the push for the city’s western section, separated from the east by the Tigris River, began the following month.

READ MORE: ISIL fighters seal off Mosul mosque for last stand

In another Mosul-related development, an international human rights group reported on Monday that at least 26 bodies of “blindfolded and handcuffed” men were found in government-controlled areas and around city since the operation started.

Human Rights Watch (HRW) said local armed forces told foreign journalists that in 15 of the cases the men were extrajudicially killed by government forces who were holding them on suspicion of being affiliated with ISIL.

HRW said that in the remaining cases that were reported by local and international sources, the sites of the apparent executions all in government-held territory raise concerns about government responsibility for the killings.

“The bodies of bound and blindfolded men are being found one after the other in and around Mosul and in the Tigris River, raising serious concerns about extrajudicial killings by government forces,” said Lama Fakih, deputy Middle East director at HRW.

“The lack of any apparent government action to investigate these deaths undermines the government’s statements on protecting detainee rights.”

Extrajudicial executions during an armed conflict are war crimes and if widespread or systematic, carried out as part of policy, would constitute crimes against humanity, HRW said.

mosul control map infographic [Al Jazeera]

Mosul fell to ISIL in the summer of 2014 as the fighters swept over much of the country’s north and central areas.

The UN estimates almost 10,000 people fled from Mosul’s northwest and the Old City every day last week.

More than 750,000 people have been displaced from the city since October. Twelve camps for the displaced have been set up in the surrounding area.