Nationalist school operator Moritomo Gakuen in Osaka hired a waste disposal service to backfill waste found at the heavily discounted construction site where it is building a new elementary school, an employee of the disposal firm says.

The school is also being probed about the nature of the land purchase, how it got such a favorable discount from the government and hate speech allegations involving its clients.

About half of the dirt-and-waste mixture excavated from the site was reburied, according to a man who works for the contractor.