In a sign of its increasing desperation, the Islamic State (ISIS) is dispatching suicide bombers even as young as seven years old to try and hold off the advancing Iraqi forces besieging the ISIS-held city of Mosul.

One such boy wearing an explosives belt was recently caught by Iraqi security forces hiding among families that were fleeing Mosul, U.K.'s Daily Star reported.

A video uploaded to video-sharing site LiveLeak shows the boy, who appears to be about 7 years old, being disarmed by an Iraqi army bomb expert.

In the video, the soldier explains that the boy was instructed by his uncle to target "the army."

At one point, the bewildered-looking boy flinches as the soldier carefully disarms the improvised explosives device wrapped around the boy's waist. The soldier reassures the child, saying: "Don't be afraid."

In another sign of ISIS desperation, the jihadist group executed its own appointed judge for refusing to fight, sources told Iraqi News on Tuesday.

The sources said the judge of the so-called Tigris State was beheaded after he refused to take part in an ISIS attack on Iraqi security forces in Mosul.

The jihadist group has reportedly adopted a new strategy compelling its leaders to fight and to encourage local people to join the fight in the battle for Mosul.

Iraqi forces are evacuating civilians from parts of Mosul to allow troops to clear the area. However, they are being hampered in their mission by ISIS snipers, according to Reuters.

The news agency said as many as 600,000 civilians remain trapped in the western sector of Mosul.

Iraqi security forces, backed by a U.S.-led international coalition, liberated several cities from ISIS last year, including eastern Mosul in December.

Battles in the western sector of the city are proving much more difficult due to the density of residential areas and the high number of civilians, officials said.

With their ranks depleted by battlefield casualties, ISIS militants have been forcing children and elderly people to carry out executions in Mosul, The Christian Post reported.

Earlier this year, ISIS released a video showing apparently brainwashed young children executing captives by shooting them in the head and cutting their throats.

Another jihadist propaganda video released last October showed ISIS "Cubs of the Caliphate" shooting some Christian captives to death while others are crucified.