A British former "church boy" was among the 1,763 ISIS jihadists whose recruitment forms were leaked this week.

Details of Fasil Towalde, who was killed while fighting for ISIS in Syria, have been revealed after his recruitment papers were among the ISIS documents handed to Sky News yesterday.

Towalde was a 21-year-old student from Camden, London, who crossed from Turkey into northern Syria on December 28, 2013 and was re-named Abdullah al-Habashi, according to the documents.

He was killed eleven months later fighting Kurdish troops for control of the Syrian border town Kobane.

On his registration form – which consists of 23 questions – he wrote his mother's first name and gave an address in Camden, where she lived.

Speaking to the Telegraph, his mother, Himan Haile, described her son as a "good Christian boy" who grew up in London, having fled violence in Eritrea.

"I am a Christian, I go to church. My child is a church boy. The bad thing is Islam," she said. Towalde was arrested during the London riots, became involved in a gang and was converted to Islam in prison, she added.

"He died for what? I don't know. Every day I cry, in the morning, in the night," she said.

There were 16 British jihadists revealed among the leaked files, at least five of whom are thought to have been killed in the last three years.

A disillusioned former member of the militant group, who called himself Abu Hamed, handed documents to Sky News on a memory stick stolen from the head of Islamic State's internal security force.

Originally a member of the Free Syrian Army, Hamed later joined ISIS but has now left the group, claiming "the Islamic rules he believed have totally collapsed inside the organisation," Sky reported.

The documents looked like enrolment forms with 23 questions and contained names of Islamic State supporters and of their relatives, telephone numbers, hometown and blood group and other details such as the subjects' areas of expertise and who had recommended them.