As for high school students, the pace of the growth was the sharpest, the survey showed.

Monthly expenditures on private education reached 515,000 won per high school student in 2017, up 43.5 percent from 2007.

Corresponding data per middle school students rose 39.5 percent to 438,000 won over a decade and that for elementary school students rose 19.9 percent to 307,000 won.

Meanwhile, the portion of low-income families' children receiving private education sharply fell over the 10 years, the survey showed.

The percentage of such elementary, middle and high school students came in at 58.3 percent in 2017, down from 77 percent in 2007. Low-income families here refer to households with monthly income of 2 to 3 million won.

In the cited period, that of children of households with 6 to 7 million won reached 80.8 percent last year, compared with 92.7 percent in 2007.

"Low-income households have little room to spend on private tutoring," said Yang Jung-ho, an education professor at Sungkyunkwan University. "A gap in private education expenditures among income brackets will likely continue to exist." (Yonhap)