At least 10 companies have been caught in a large-scale investigation into illegal child labor in Daxing district, local media reported Tuesday.

The issue of underage labor recently caught Daxing prosecutors' attention while handling a case of rape and robbery in early February, according to Beijing Times. One of the victims, surnamed Zuo, who was employed by Xinli Textile Mill in the district, was found out to be only 15 years old. The legal age for paid employment in China is 16.

The human resources and social security bureau of Daxing district put together four investigation groups on March 20 with the assistance of local police stations, city administration departments and safety supervision departments. The groups were comprised of law enforcement officials and handed the task of investigating labor employment in the district.

By Tuesday, 823 factories and 12,761 employees had undergone investigation and in total, 10 cases of underage employment were discovered, the newspaper reported.

Zhang Wenjuan, deputy director of the Chinese Juvenile Rights Center - an organization working to protect the rights of children - said child labor has been high on their agenda since the founding of the center in 1990. Zhang said she has dealt with at least 10 cases this year alone.

"Most victims are around 15 years old. They come from other provinces after completing nine years of compulsory education," Zhang told METRO.

She said the issue is connected to the current education system.

"Sadly, there is often a gap year between the legal age of adulthood and the age at which many children leave school. Given their financial burdens, they can't afford to wait until they are legally old enough to work."

"Even when they are discovered and returned to their hometowns, they usually find a way to come back," Zhang said.

"Almost all the children are too young to understand the seriousness of the matter. They don't ask for help unless they get injured, but they hardly ever receive compensation."