South Korea's government unveiled plans on Monday aimed at curbing the country's burgeoning spending on private education, which has been blamed for being a major factor behind the country's declining fertility rate.

The move comes as South Korean President Yoon suk-yeol this month criticized college entrance tests that incorporate questions not in the curriculum at public schools, including some that have been dubbed "killer questions" due to their complexity.

"We will cut the vicious cycle of killer questions in exams which leads to excessive competition among students and parents in private education," education minister Lee Ju-ho told a briefing.

The ministry also vowed to crack down on private education "cartels" by ramping up efforts to monitor what it termed false and exaggerated advertising.

South Koreans spent a record 26 trillion won ($19.97 billion) on private education last year, despite a declining student population, a joint report by the education ministry and the government statistics bureau showed.

Nearly 8 in 10 students take part in private education such as cram schools, known as hagwons, according to the report.

This heavy reliance on private education has helped result in South Korea having the world's highest cost of raising a child, according to a report last year, and the world's lowest birth rate.