The rate of sex crimes among juveniles has hiked by fivefold in Seoul in the last three years, data showed Tuesday.

According to the Seoul Metropolitan Office of Education’s report, the number of sexual assault cases jumped from 21 to 107 between 2010 and 2012.

The number for this year reached 66 as of the end of July, putting it on track to exceed last year’s figure.

While the number of cases stayed around 30 to 40 before 2012, the figure started to increase sharply, apparently as a result of various factors, experts say.

“The methods through which the students can report cases expanded upon the revision of the school violence prevention regulations after a series of high-profile sexual crimes against teenagers in the summer of 2012,” said Lee Soo-jung, forensic psychology professor at Kyonggi University.

“They now can more conveniently report the assault online. The improved administrative support has also played a role (in the number of cases),” Lee said.

The number of punished students consequently soared from 44 in 2010 to 182 two years later.

A total of 106 pupils received disciplinary measures in the first half of this year.

The common types of punishment also changed over the period.

School transfer was the most common disciplinary measure until 2012, when special education became the main form of punishment. These were followed by a letter of apology, school voluntary work and suspension depending on the degree of violence. Last year, a total of 72 students received special education, whereas 18 students were forced to transfer to a different school.

Among the offenders since 2010, 275 students were from middle school, followed by 71 high schoolers and 20 elementary school pupils.

Some observers said more attention should be paid to taking preventive measures against the sex crimes among minors, in addition to punishment.

“Sometimes, adolescents think that sexual violence is all a part of a joke. They don’t know how much damage they are inflicting on the victim. We should increase more human-rights-related classes and other social-issues-related education,” said Jung Hakyeong-ju from the Korea Women Link Sexual Violence Relief Center.

By Lee Hyun-jeong  (rene@heraldcorp.com)