Beirut: Decades of reckless arms trading and the poorly regulated flow of weapons into Iraq have contributed to Daesh’s accumulation of a “vast and varied” arsenal which is being used to commit war crimes on a massive scale in Iraq and Syria, an international rights group said Tuesday.

Amnesty International’s report, based on expert analysis of verified videos and images, says most of the extremist group’s weapons, ammunition and equipment were looted from the Iraqi army. It says the weapons were manufactured and designed in more than two dozen countries, including Russia, China, the US and EU states.

Daesh swept across Iraq in the summer of 2014, capturing the second largest city, Mosul, and taking weapons left behind by fleeing Iraqi security forces, including US-supplied arms and military vehicles. The extremist group has also snatched arms from Syrian forces after capturing military bases there.

“The vast and varied weaponry being used by the armed group ...[Daesh] is a textbook case of how reckless arms trading fuels atrocities on a massive scale,” said Amnesty researcher Patrick Wilcken.

“Poor regulation and lack of oversight of the immense arms flows into Iraq going back decades have given Daesh and other armed groups a bonanza of unprecedented access to firepower,” he said.

The rights group said the weapons have allowed Daesh to carry out a “horrific campaign of abuse,” including “summary killings, rape, torture, abduction and hostage-taking — often carried out at gunpoint”.

Amnesty said the range and scope of the group’s arsenal reflects decades of “irresponsible” arms transfers to Iraq. It also faulted a lack of oversight following the 2003 invasion, when the United State spent billions of dollars arming and training Iraqi security forces. “Lax controls over military stockpiles and endemic corruption by successive Iraqi governments have added to the problem,” it said.

The report documents the extremists’ use of arms and ammunition from at least 25 countries. Among the advanced weaponry in the Daesh arsenal are man-portable air defence systems, or MANPADS, guided anti-tank missiles and armoured fighting vehicles.

It said most of the conventional weapons being used by Daesh fighters date from the 1970s to the 1990s, when Iraq was engaged in a massive military buildup ahead of and during the 1980-1988 Iran-Iraq war.

On Monday, analysis firm IHS said that Daesh is pulling in some $80 million (Dh293.6 million) a month, mainly from levies and confiscations, but is struggling financially as strikes hit its oil infrastructure, .

In a new report, IHS Conflict Monitor said that Daesh, unlike other militant groups such as Al Qaida, does not need to rely on foreign funding as it can count on revenues from the large parts of Syria and Iraq under its control.

Using open source intelligence including social media and sources inside the countries, IHS said it estimates the group’s overall monthly income to be around $80 million as of late 2015.

About half the revenues come from levies and confiscations, with Daesh slapping a 20 per cent charge on all services, IHS said. Some 43 per cent comes from oil sales and the rest from drug smuggling, electricity sales and donations.

“Daesh controls the state so they tax the population, confiscate property, can produce income from state-run businesses and from oil and gas. Other terrorist groups don’t have that,” said Columb Strack, senior analyst at the London-based IHS.

But other groups also do not have significant territory to rule, so “it’s not like they are making $80 million and spending all of that on weapons and building bombs,” he said.

The group has not followed its sweeping offensive of 2014 with other major gains and IHS said it is now having trouble making ends meet.

“There are early indications that the group is struggling to balance its budget, with reports of cuts to fighters’ salaries, price hikes on electricity and other basic services, and the introduction of new agricultural taxes,” IHS said.