Recruits to Islamic militant groups are likely to be well educated and relatively wealthy, with those aspiring to be suicide bombers among the best off, a study by the World Bank has found.

The research, based on internal records from the Islamic State group, will reinforce the growing conclusion among specialists that there is no obvious link between poverty or educational levels and radicalisation.

The data, leaked by a disaffected former member of Isis in March, includes basic information on 3,803 foreign recruits from all over the Islamic world and Europe who joined the organisation between early 2013 and late 2014, when the flow of volunteers to the organisation reached a peak.

Those arriving in Isis-controlled territory were vetted and interviewed. Data on country of residence, citizenship, marital status, skills, educational status, previous extremist experience and knowledge of Islamic law was recorded.

The World Bank study found that 69% of recruits reported at least a secondary level education while “15% left school before high school and less than 2% are illiterate”.

The educational level of recruits from north Africa or the Middle East was significantly greater than that of most of their compatriots, the researchers found.

“A large fraction have gone on to study at university … Recruits from Africa, south and east Asia and the Middle East are significantly more educated than individuals from their cohort in their region of origin,” the report said.

The recruits were also asked by Isis what role they hoped to play within the group. The proportions of those who wanted to be administrators and “suicide fighters” increased with education, the report’s authors noted.

Neither inequality nor poverty was a driver of involvement in violent extremism, and wealthier countries were more likely to supply foreign recruits for Isis, the report found.

“In countries with a large Muslim population, low degrees of religiosity, low levels of trust in religious institutions and strong government and social control of religion seem to be risk factors of radicalisation,” the report said.

Ongoing research into causes of Islamic militancy has underlined the complexity of motives of recruits and volunteers, as well as the differences between different conflict zones.

Earlier this week, a report into Boko Haram, the Isis-affiliated Islamist group in Nigeria, found that female members of the brutal organisation were almost as likely as men to be deployed as fighters, challenging a widespread perception that women are mainly used as cooks, sex slaves and suicide bombers.

Isis’s attitude to using women as fighters has evolved, and varies according to local circumstances. Female recruits have not taken up combat roles in areas the group controls in Iraq and Syria but are increasingly deployed tactically, or at least encouraged to execute terrorist operations in Europe and elsewhere. An alleged terrorist cell dismantled in Morocco last week included women.

The research by Finn Church Aid, a Finnish NGO, also found that economic factors were important in drawing people in north-east Nigeria into extremist violence.

Boko Haram has killed about 15,000 people and displaced more than 2 million in Nigeria in a seven-year insurgency. Photograph: STR/AP

Religious beliefs, poverty, a lack of education and work, and opportunities offered by Boko Haram were cited by the former militants interviewed by researchers as the main reasons for joining the group.

While men in Boko Haram dominate leadership and training roles, women may outnumber them in other senior roles, such as recruiters and intelligence operatives, said the report, which was based on interviews with 119 former Boko Haram members.

Four in 10 female respondents said they served as soldiers – compared with 45% of men – while both sexes carried out domestic tasks like cooking and cleaning.

“Recruiters are adapting to the tightening security environment,” Mahdi Abdile, director of research at Finn Church Aid and co-author of the study, told Reuters, adding that women and girls were increasingly being targeted for recruitment.

“The intelligence community is on the lookout for young men, so it is easier for women to navigate past security barriers and penetrate communities,” he said.

Boko Haram has killed about 15,000 people and displaced more than 2 million in Nigeria in a seven-year insurgency, and still launches attacks despite having been driven out of much of the territory it held in 2014.

The Islamic militant group has stepped up suicide bombings carried out by children in recent years, many of them carried out by girls, according to the UN children’s agency Unicef.

But women in Boko Haram have long been involved in planning logistics, planting mines and bombs, and fighting as soldiers, said Vincent Foucher of the International Crisis Group.

The report also found that six in 10 of the former militants – who are undergoing rehabilitation programmes – were introduced to Boko Haram by friends and relatives, while only a quarter learned about the group at mosques or Islamic schools.

“Mosques and [Islamic schools] used to be the place to get new recruits … now they are under the spotlight,” said Abdile.

The same displacement of recruiting activities by Islamic militants has been observed elsewhere, including the UK, Belgium and France. The shift presents a significant challenge for overstretched security agencies.

A report earlier this year by Mercy Corps, the US-based aid organisation, found that Boko Haram had recruited young entrepreneurs and business owners by providing or promising capital and loans to boost their businesses.

The Nigerian economy is in serious trouble, while in its most recent economic update, the World Bank Real noted that GDP growth in the Middle East and north African regions for 2016 is projected to fall to 2.3%, its lowest level since 2013 and lower than last year’s growth by half a percentage point.

“Policies that promote job creation, therefore, not only benefit young people seeking jobs but may help thwart the spread of violent extremism and its attendant effects on national and regional economic growth,” the World Bank researchers said.