Transparency International says corruption is one of the root causes of violent extremism.
The anti-corruption watchdog says the international community needs to make tackling corruption a top priority in the ongoing battle against extremist groups such as Islamic State and Boko Haram.
In a report released Tuesday Transparency International says government corruption allows militants to take advantage of public anger to fuel recruiting, facilitate arms flows, and undermine public institutions such as the military - leaving them incapable of controlling extremist threats.
"The international community expends great efforts tackling the 'ideology' of groups such as ISIS, focusing on the religious rhetoric they produce, yet completely ignoring the material circumstances in which they thrive," said Katherine Dixon, director Transparency International Defense and Security.
The report cites the ability of Islamic State fighters to seize the key Iraqi city of Mosul in 2015 as it swept across large portions of northern and western Iraq and also eastern Syria. Mosul quickly fell in part because Iraqi forces were unable to defend the city that is today the focus of a major offensive to reclaim control from the militants.
Islamic State also had success capitalizing on the lack of stability in Libya that has persisted since the overthrow of longtime leader Moammar Gadhafi, though the group has lost much of the area it once controlled there.
Transparency International says extremists in Libya are able to make their case based on a corruption narrative that is hard to counter because of the history of corruption there, as well as the transitional government's inability to provide a stable security environment for Libyans.
The report also cites the Nigerian militant group Boko Haram, saying its early years included a foundation of anti-corruption and anti-elite rhetoric.
"Abuses by the security forces and high levels of fraud and corruption in the army meant the group's message resonated," the report says.
In the case of Islamic State, Transparency International says the group's messaging portrays itself as pure in a way that governments in the Middle East are not.
"ISIS's message is clear: governments in power are corrupt, bent towards the interests of a narrow, unrepresentative elite. They fail to provide services for their citizens; ISIS, on the other hand, is focused on justice, good governance and the provision of services," the report says.
Transparency International says those messages have resonance with Iraqis and Syrians who have dealt with "violent foreign interventions and decades of sectarian inequalities."
"Perhaps what is most concerning about the group is not its fanaticism, but its ability to unite fanaticism with messages that resonate with a frustrated public, to violent ends."