ISIS documents found by Iraqi forces in Mosul show the terrorist group had troubles with foreign "problem" fighters, the Washington Post reports.
The files show that some fighters simply refused to fight in Iraq, while others were more creative. A Belgian man brought in a medical note saying he could not fight because of back pain. Another man said he could not fight because he had a headache.
A 24-year-old French militant of Algerian descent said he did not want to fight and wanted to leave the country to go back home to carry a suicide attack. He also said he was ill but did not have a "medical report."
The file shows that rebellion seemed to have been brewing within a unit made up mostly of foreigners and documented 14 "problem" fighters. The documents were discovered in a Mosul neighbourhood used for administrative purposed by the Tariq Bin Ziyad battalion, whose fighters are described in the files.
Although thousands of foreign fighters joined ISIS' ranks over the past few years, the group's appeal has greatly diminished as it has lost much of its territory and revenues in Iraq and Syria.
"Several countries such as France, Belgium and the United States have indicated that the number of Foreign terrorist fighters travelling to Syria and Iraq has dropped significantly, with other countries expecting the number to drop in the foreseeable future,"the International Centre for Counter-Terrorism (ICCT) reported in December 2016.
The Islamic State's losses have caused authorities to warn that with foreign fighters coming home, more attacks were to be expected in Europe. The ICCT estimates that there are 15,000 foreign fighters in Syria and Iraq and that the number of returning fighters, especially to the EU and North Africa, will rise.
The documents contain pictures of the militants, their names, date of birth, country of origin and residency. They also list their weapons specialities, and the number of wives, children and "slave girls" each fighter had.
Foreign fighters were a big part of the ISIS militants with up to 4,000 joining the group from the EU alone, they were also often described as their most vicious fighters. The ICCT also reported that most foreign fighters in Iraq and Syria were from North Africa the Middle East and Central Asia but that "significant numbers" were also from Europe and South-East Asia.
"Those foreign fighters are the most furious fighters we ever fought against," Lt. Col. Muhanad al-Tamimi told the Washington Post. "When those fighters refuse to fight, it means that they’ve realised this organisation is fake Islam and not the one they came for."
Read the full Washington Post report here.
Join the conversation about this story »
NOW WATCH: A Nobel Prize-winning biologist reveals how to slow down the effects of aging