Nickolay Mladenov, the envoy of UN Secretary General Ban Ki-moon in Baghdad, made the remarks before the UN Security Council on Wednesday.
Mladenov rapped the terrorists’ "recruiting and using foreign fighters, engaging in murder, hostage-taking, kidnappings, gross human rights violations."
The UN envoy called on the international community to “cooperate in efforts to enforce existing sanctions and hold accountable the perpetrators."
Meanwhile, a female former candidate for parliament was killed by the terrorists in the ISIL-held town of Sharqat in the northwest of the Iraqi capital.
The bodies of eight Iraqi soldiers and allied fighters, executed on Tuesday, were also found in the north of holy city of Samarra.
ISIL executed four men in Jalawla, northeast of Baghdad, because their brothers were policemen.
The crisis in Iraq escalated after the ISIL terrorists took control of Mosul, in a lightning advance on June 10, which was followed by the fall of Tikrit, located 140 kilometers (87 miles) northwest of the capital.
More than one million people have been displaced in Iraq so far this year, according to the UN.
Soldiers of the Iraqi army, backed by tribal forces and volunteers, have been engaged in heavy fighting with the militants on different fronts and have so far been able to push back militants in several areas.
NTJ/NJF