Dozens of Isis recruits have left the Islamic militant group partly because the luxury goods and cars they were promised before they joined failed to materialise, a new paper has found.

The report, entitled 'Victims, Perpetrators, Assets: The narratives of Islamic State defectors' looks into the reasons why enthusiastic Isis recruits may have changed their mind and decided to defect from the militant group.

Published by London-based think tank The International Centre of the Study of Radicalisation and Political Violence (ICSR), the report gives an interesting insight into why defectors left, with stories that the ICSR believes could be vital in stemming the flow of foreign fighters travelling to Syria.

The ICSR identified four main narratives in the stories of 58 defectors from Isis, who came from 17 different countries. One of these was the "harsh and disappointing" realities of life under Isis.

Ancient monuments under Isis threat Show all 8 1 /8 Ancient monuments under Isis threat Ancient monuments under Isis threat Isis seizes Palmyra The ancient oasis city of Palmyra Getty Ancient monuments under Isis threat Isis seizes Palmyra A partial view of the ancient ruins Getty Ancient monuments under Isis threat Isis seizes Palmyra The ancient Palmyra theater Reuters Ancient monuments under Isis threat Isis seizes Palmyra A view of the ancient Syrian city of Palmyra Getty Ancient monuments under Isis threat Isis seizes Palmyra The Temple of Bel Reuters Ancient monuments under Isis threat Isis seizes Palmyra Palmyra's famous graves AP Ancient monuments under Isis threat Isis seizes Palmyra The ancient castle Getty Ancient monuments under Isis threat Isis seizes Palmyra A sculpture depicting a rich family from the ancient Syrian oasis city of Palmyra, displayed at the city's museum Getty

They point out that those who left due to these realities usually joined for 'selfish' reasons - because they wanted the life of luxury that they were promised by Isis propaganda.

Others described their actual duties within Isis as dull and boring, complaining about the lack of actual fighting and the claims that foreign fighters were exploited.

Beyond the underwhelming nature of life under Isis, which is generally presented as utopian by online propaganda, the other main reasons for leaving were less materialistic.

Many of the defectors included in the report objected to the brutality of the group - in particular, its extreme violence to innocent civilians and hostages.

Displaced people from the minority Yazidi sect flee Isis in Al-Hasakah Governorate. Many Isis defectors said they were encouraged to leave by the group's brutality to innocent civilians. (Getty)

Others took issue with the violence Isis fighters themselves are subjected to - with some describing the execution of fighters by their own commanders.

However, the report pointed out that this was not a "universal concern", but was most sharply felt when it was other Sunni Muslims being subjected to violence.

One of the defectors' "persistent criticisms" was the extent to which Isis is fighting against other Sunni rebel groups, rather than focusing on fighting Assad's government forces.

They also took issue with the squabbling and in-fighting within Isis, and with the leadership's obession with "spies" and "traitors" within its ranks.

Another main criticism was the perceived corruption within the group - Syrian defectors from Isis complained about the privileges given to foreign fighters, where others pointed out more direct racism within the group, such as one Indian Isis recruit who was forced to clean toilets due to the colour of his skin.

Fresh territory: an Isis fighter in Raqqa, Syria, last year (Reuters)

In the opening paragraph of the report, it describes a moment when a British Isis fighter phoned ICSR research fellow Shiraz Maher, complaining that in reality, Isis' 'jihad' consisted of "Muslims fighting Muslims," while Assad was "forgotten about."

The overarching reason for their defections seems to be how different life under Isis actually was, when compared to what they had been lead to believe. The ICSR hopes that these stories can be used to keep young men and women from becoming radicalised and travelling to join Isis.