A police investigation has confirmed what has been widely suspected: rampant illegal practices at private nursery schools. Yet the pervasiveness of corruption laid bare by the investigation leaves us at a loss for words.

The police station in Songpa, a southeastern district in Seoul, said on Monday that it has booked 55 nursery operators in southern Seoul on suspicion of embezzling government subsidies and receiving rebates from teachers offering extracurricular programs.

The station started to investigate day care centers in Songpa four months ago. But it had to expand its probe beyond Songpa as nurseries in other districts were found to have been involved in similar irregularities.

It has thus far confirmed that some 700 child care facilities in southern Seoul, which includes Gangdong, Seocho, Dongjak and Gwanak districts as well as Songpa, have broken the law. The 55 operators were the first batch of the alleged lawbreakers to be booked.

According to investigators, the most frequently used illicit practice involved extracurricular activities. Nurseries are required to organize extracurricular programs for children twice a week, each session lasting one hour.

Many nurseries were found to overcharge parents for extracurricular activities and underpay outside lecturers they invited to offer those programs. They cut program hours and had lecturers pay back up to 80 percent of the fees they had been formally paid for their services.

They are also suspected of having misappropriated government subsidies by exaggerating the number of teachers they employ and children they look after.

One nursery director identified as Chung registered her husband and daughter as teachers, although they had no license, and received government wage subsidies for them.

Some nursery operators registered unqualified assistant teachers as homeroom teachers to make them eligible for government subsidies.

The list of irregularities allegedly committed by these nurseries also includes serving subpar meals to the children after receiving large amounts from parents under the pretext of only using organically grown food for the meals.

Through these and other illegal means, the 700 or so nurseries have allegedly embezzled public funds and parents’ money amounting to 30 billion won over the past three years.

But this is only the tip of the iceberg. Corruption at child care facilities in other parts of the nation is expected to be worse than that at those in southern Seoul. The police need to expand their probe nationwide.

Lawmakers should revive the bill designed to give central and local government officials in charge of child care the same investigative power as that of judicial police officers. The bill was killed under pressure from nursery owners,

President Park Geun-hye urged officials at Cheong Wa Dae on Monday to speed up the construction of workplace nurseries. To be sure, expanding on-site care centers will help. But the fundamental solution is to build more public facilities.

Currently, state-run institutions account for less than 6 percent of the nursery schools across the nation. This share needs to be raised to around 30 percent to ensure that the forces of competition exert pressure on private facilities to improve their services.