JAPANESE Prime Minister Shinzo Abe was grilled by opposition MPs in parliament today over a widening school land sale scandal linked to his wife, as his government’s approval ratings plunged to their lowest levels.

MPs renewed demands that Mr Abe’s wife and top officials involved in the land sale be summoned to testify in parliament. Mr Abe has denied wrongdoing.

Smouldering for a year, the scandal erupted again last week after Finance Ministry officials acknowledged tampering with land sale documents, including deleting references to Akie Abe, following a newspaper report in early March. The tampering is under criminal investigation by prosecutors.

Constitutional Democratic Party of Japan MP Tetsuro Fukuyama accused Mr Abe of betraying parliament for nearly a year.

“The Abe government’s attitude is entirely called into question,” Mr Fukuyama said.

Four opinion polls released today showed government approval ratings falling to the 30 per cent range, the lowest since Mr Abe took office in 2012.

Thousands of protesters have gathered outside the prime minister’s office almost every day, demanding that he step down.

The scandal stems from the 2016 sale of state land to school operator Moritomo Gakuen in Osaka at one-seventh the appraised value with the alleged involvement of Ms Abe, who has said both she and her husband support the school’s ultra-nationalistic philosophy of education.

Ministry officials said the land deal documents were altered from late February to April last year at the instruction of the financial bureau, the ministry department in charge of state property transactions, mostly at its regional unit in Osaka.

That coincided with Mr Abe’s pledge to parliament that he would resign if any proof of the allegations were found.