Men with a history of sexual violence and domestic abuse joined Islamic State because of the organisation’s systemic use of rape and slavery as a form of terrorism, according to new analysis.

The promotion and sanctioning of sexual violence by the extremist group was a pivotal means of “attracting, retaining, mobilising and rewarding fighters” as well as punishing kaffir, or disbelievers, says a report to be released by the Henry Jackson Society.

Enshrining a theology of rape, the sexual exploitation of women alongside trafficking helped fund the caliphate and was used to lure men from deeply conservative Muslim societies, where casual sex is taboo and dating prohibited.

In addition, forced inseminations and forced pregnancies – along with forced conversions – were officially endorsed to help secure the next generation of jihadis, a tactic also replicated by Nigeria’s militant Islamist group Boko Haram.

Analysis of Isis members from Europe and the US found that a cohort had a history of domestic and sexual violence, suggesting a “relationship between committing terrorist attacks and having a history of physical and/or sexual violence”.

One Briton, Ondogo Ahmed, from north London, was given an eight-year custodial sentence for raping a 16-year-old girl in the UK but fled to Syria while out of prison on licence in 2013.

Another was Siddhartha Dhar, a father of four from London, who has been described as a central player in Isis’s brutal persecution of the Yazidis, a religious minority whose followers the group permitted its members to rape.

Testimony from one victim, Nihad Barakat, 18, revealed how Dhar, a former bouncy castle salesman from Walthamstow, east London, routinely participated in the group’s systemic trafficking and abuse of Yazidi teenage girls and enslaved some himself. “These cases indicate an existence of a type of terrorism that is sexually motivated, in which individuals with prior records of sexual violence are attracted by the sexual brutality carried out by members of Islamic State,” said Nikita Malik, the report’s author.

Although Malik said more work was required to establish a definitive link between an individual’s history of domestic violence and subsequent involvement in terrorism, evidence existed to indicate a potential correlation. One of the men involved in July’s London Bridge attack, Rachid Redouane, 30, was reportedly abusive and controlling, and his girlfriend eventually fled to a unit for victims of domestic violence. The Westminster attacker Khalid Masood, 52, is another who has been described as violent and controlling, this time towards his second wife.

Isis has repeatedly promoted and attempted to legitimise a theology of rape, occasionally through its Dabiq magazine and Al Hayat media channel. One edition of Dabiq justified the rape of Yazidi women in Iraq by dismissing them as “pagans”. The extremist group also set up a department dedicated to “war spoils” and issued guidelines to codify slavery.

Markets selling sex slaves were relatively common in territory controlled by Islamic State in Iraq and Syria at the calpihate’s height, while the group’s franchise in Libya has also played a role in human trafficking. One account contained in the report describes how Isis members would touch the chests of girls to see whether they had grown breasts. If they had done so they could be raped, according to the report – which will be released in parliament – and if not they would be examined three months later. Among a number of harrowing case studies are accounts of how a 10-year-old Libyan child was raped by traffickers linked to Isis.

Apart from subjugation and spreading terror, another key reason for Isis exploiting sex trafficking is financial gain. Ransom payments directly linked to the threat or use of sexual violence and paid out by governments and individuals earned, according to the report, between £7.7m and £23m last year, at a time of lowering revenues for the group.

Analysis of sales contracts notarised by Isis-run Islamic courts reveal that ransom payments demanded by Isis for captive slaves confirm that the organisation viewed it as a way of making money. Documents show that one female slave was bought from Isis in Raqqa for $13,700, while another was sold for $15,300 via an online advert. Some slaves, however, were sold extremely cheaply, one for as little as £6 through an internal Isis market. The highest ransom fee was £35,000, placed for a captive woman held in Raqqa, the caliphate’s capital, which is on the brink of falling to US-backed fighters.

Among a number of recommendations, the report calls for the British government to create a dedicated legal unit to work with NGOs, charities and embassies to determine the nexus between sexual violence, traffickers and terrorist organisations.

The government’s former independent reviewer of terrorism legislation, Lord Carlile, said: “This report highlights the imperative need for more international co-operation to break up the trafficking gangs and routes, which are so essential for their wicked trade in human beings.”

Labour’s Yvette Cooper, who chairs the home affairs select committee, said such recommendations should be considered by the government. “It is vital the complex relationship between human trafficking, sexual violence and both the funding for – and tactics deployed by – terrorist groups is fully understood and reflected in domestic and international law if we are to effectively combat these dangerous organisations.”

Henry Smith, MP for Crawley and a member of the international development committee, said: “It is clear that sexual violence is prevalent in human trafficking and in terrorism – and, abhorrently, human trafficking is becoming more closely related to terrorism.”

Malik said sexual violence needed to be prosecuted as a tactic of terrorism. “In the UK, laws including the modern slavery and terrorism acts should be interpreted more broadly, in order to adequately reflect the spectrum of crimes committed by individuals using sexual violence as a tactic of terrorism,” she said.