The 18-year-old Hamad al-Tamimi says he was recruited online by ISIL when he was a religious studies student in Riyadh, Saudi Arabia, press tv reported.
Tamimi, who was arrested by Iraqi troops during a military operation in Iraq’s Western province of al-Anbar, said that he left Saudi Arabia for Kuwait in July and from there he moved to Turkey before joining the ISIL Takfiri militants operating in Syria.
Tamimi is known by his nom de guerre as Abu Walid.
"There are many nationalities," CNN quoted him as saying. "From Norway, from America, Canada, Somalia, Korea, China, Turkmenistan, Tajikistan, Uzbekistan, Egypt, Libya, Tunisia, Lebanon and other European countries such as Germany and France," Tamimi stated.
A CIA source said more than 15,000 militants from 80 countries are operating in Syria and Iraq.
"From Germany, I knew Abu Hamza, and from Britain one named Abu Dawoud, and from America one named Abu Ibrahim," Tamimi said, adding that all the individuals were young.
The Saudi national said he had to swear allegiance to the so-called ISIL leader, Abu Bakr al-Baghdadi, after 22 days at a religious indoctrination camp.
He added that he received military training at an air base in the Syrian city of Raqqa.
Tamimi said after a short time spent in Aleppo, Northwestern Syria, the order came to move across the essentially nonexistent border into Iraq, where ISIL militants operating against Iraqi forces near the Haditha Dam needed reinforcement.
The ISIL terrorists are in control of some areas in Syria and have captured large swathes of land in neighboring Iraq.
They are notorious for carrying out horrific acts of violence, including beheading the captives, in the areas they have overtaken.