Amnesty International has reported that the prolonged inflow of poorly regulated arms into Iraq has contributed to a growth in Islamic State (IS) terrorist crimes.
An Amnesty report, entitled 'Taking Stock: The arming of Islamic States', document IS' use of arms and ammunition from at least 25 different countries, including the US, Russia and former Soviet bloc states.
According to the report, the arms were originally intended to be used by Iraqi forces.
Amnesty International Arms Control, Security Trade and Human Rights researcher Patrick Wilcken said: "The vast and varied weaponry being used by the armed group calling itself Islamic State is a textbook case of how reckless arms trading fuels atrocities on a massive scale.
"Poor regulation and lack of oversight of the immense arms flows into Iraq going back decades have given IS and other armed groups unprecedented access to firepower."
The report states that during the Iran-Iraq war, roughly 34 countries supplied Iraq with weapons, while 28 of those same states were also simultaneously supplying arms to Iran.
After Iraq's invasion of Kuwait in 1990, a UN arms embargo cut imports until 2003, but resumed them after the US-led invasion Iraq.
In recent years, the Iraqi Government has signed contracts worth billions of dollars with the US to supply equipment, including 140 M1A1 Abrams tanks, F16 fighter aircraft, 681 Stinger shoulder-held units, Hawk anti-aircraft batteries.
The US has also delivered small arms and ammunition worth more than $500m to the Iraqi Government.
Targeted terrorist attacks at military installations and camps have resulted in the loss of the Iraqi force's arms supply, including the capture of 2,300 Humvee armoured vehicles from the northern city of Mosul, Iraq, in 2014.
According to the report, the IS weapon supply includes man-portable air defence systems (MANPADS), guided anti-tank missiles, and armoured fighting vehicles, as well as assault rifles like the Russian AK series, and the US M16 and Bushmaster.
In the wake of the latest findings, Amnesty has called on all states to adopt a complete embargo on Syrian Government forces and the terrorist groups.
The human rights organisation has recommended the adoption of strict risk assessments prior to exporting arms to Iraq.