Footage of a convoy of the militants passing through Mosul on Tuesday showed young boys toting what appeared to be assault rifles and sitting in trucks full of militants, the Independent wrote.
US weapons and ammunition were among the hoard.
According to the Human Rights Watch ISIL militants in Syria have already recruited children as snipers and suicide bombers.
The number of children killed in the growing conflict in Iraq so far is unknown but footage has shown them being drawn into the bloodshed by extremist militants.
On Tuesday, images emerged of children apparently being encouraged by ISIL militants to watch executions.
On June 10, the Takfiri militants took control of the Nineveh provincial capital Mosul, in a lightning advance, which was followed by the fall of Tikrit, located 140 kilometers (87 miles) northwest of Baghdad.
Atrocities including beheadings, executions and massacres have been reported and thousands of civilians fearing for their lives have fled.
The ISIL has vowed to continue its raid towards Baghdad.
Iraqi Prime Minister Nouri al-Maliki has said that the country’s security forces would confront the terrorists, calling the seizure of Mosul a clear conspiracy.
SHI/SHI