The ruling parties agreed Wednesday they are ready to summon to the Diet a key figure in the altering of Finance Ministry documents related to the controversial sale of state-owned land to school operator Moritomo Gakuen at a massively discounted price.

Former National Tax Agency head Nobuhisa Sagawa, who resigned over the scandal on Friday, is considered a likely witness to the transaction. He has come under scrutiny for allegedly making false remarks to the Diet while serving as chief of the ministry's Financial Bureau in charge of overseeing the land sale.

The opposition camps had demanded that Sagawa appear before the Diet to make clear why settlement documents were rewritten and whether the ministry was urged to do so by politicians.