Warnings against online misconduct were issued to 220 minors under 18 in the first half of the year, the National Police Agency reported Thursday.

The warnings covered activity ranging from paid sex and dates to underwear sales, and 102 were involved in prostitution or other illegal acts before meeting the officers.

The warnings were issued as part of a nationwide system introduced last October that allows police to contact minors involved in such solicitation without identifying themselves as law enforcement officers, meet them in person and deliver correctional guidance.

The system is designed to help protect minors before they get involved in such crimes, which could lead to further underworld involvement. Girls accounted for 210 of the minors, who included 143 high school students, 25 in junior high and 45 truants or jobless students.