A growing number of "disillusioned" Islamic State fighters are defecting from the jihadist group and could be used by governments to deter potential recruits, a report published Monday said.

At least 58 people have left the group and publicly spoken about their defection since January 2014, according to the report by the International Centre for the Study of Radicalisation and Political Violence (ISCR) at King's College London.

The study said that 17 fighters were reported to have defected in June, July and August alone, adding that they represent only a "small fraction" of former fighters, with many too scared to come forward.

The ISCR called on governments to make it easier for defectors to speak out, without the threat of prosecution, as a deterrent to others.

Those who told their stories overwhelmingly said they were disaffected by the killing of fellow Sunni Muslims, including innocent civilians, and the group's failure to confront the regime of President Bashar Al-Assad.

"The defectors' voices are strong and clear: 'IS is not protecting Muslims. It is killing them,'" the report said.

Read more: AFP via Yahoo News