Turkey banned the crossing of its border with Syria for anyone except Syrian citizens last summer, but necessary documents can be easily purchased on the black market, according to smugglers who bring people across the border.
"It helps if they want to go — they have a whole new identity, which can get them across to the other side," one of the smugglers told the media outlet.
A fake document costs around 500 pounds ($775) per passport.
Earlier in the week, UK police announced that three London schoolgirls are believed to have crossed into Syria from Turkey to join ISIL.
Islamic State controls large areas of Syria and Iraq. The group actively recruits foreigners under its banners. US National Counterterrorism Center estimates that 20,000 people from around the world have joined IS.
A US-led coalition comprising more than 60 countries is conducting air strikes against the militants.
