Osaka officials Friday launched an on-site investigation into allegations of fraud involving private school operator Moritomo Gakuen's construction costs for a new elementary school.

The prefectural investigation comes as Diet members weigh calling for a parliamentary investigation into allegations made by Moritomo head Yasunori Kagoike in sworn testimony earlier this month that Prime Minister Shinzo Abe's wife, Akie, donated ¥1 million to the new school. Both have denied the allegations.

Friday's investigation took place at Moritomo Gakuen headquarters with Kagoike present as prefectural officials looked into whether he committed fraud when submitting three different figures to three different entities detailing the construction costs for a new elementary school he wanted to build in Toyonaka, Osaka Prefecture. The school was scheduled to open this month.