AlQa'dah 14, 1434, Sep 20, 2013, SPA -- More than 4,000 Syrian children have crossed borders into neighboring countries without parents or adult relatives, the U.N. Children's Fund (UNICEF) said Friday, warning that without the protection of guardians, they remain extraordinarily vulnerable to exploitation and abuse. UNICEF spokeswoman Maxine Mercado told reporters in Geneva that many of the children "were working to provide income back to families, and were desperate to get back to school." Of the 4,150 Syrian children identified and registered, at least 1,700 are in Lebanon, where in the Bekaa Valley area, many were used for agricultural child labor. Jordan is home to about 1,170 children, mostly in the Za'atari camp, which has become the country's fourth-biggest city. In Iraq, the children's agency estimated there were 300 newly arrived, unaccompanied children in the north. "Each of those children had witnessed or been a victim of horrific levels of violence," Mercado said, adding that some children fled from fighting, while others sought relatives who had left earlier. UNICEF was working with partners to identify the children and make sure they are being protected, as well as providing medical, psychosocial, and educational support, Mercado said.