He did not directly respond to a question about media reports that the name of Prime Minister Shinzo Abe's wife, Akie, had been removed from documents related to the sale, which the government admitted on Monday had been altered.
"I take people's criticism sincerely and want Finance Minister (Taro) Aso to be responsible for pushing ahead with an investigation to fully reveal why this kind of incident happened", added Abe.
"What is important is to make everything clear", he said.
Tamaki also said Aso can not escape his responsibility anymore, adding that the scandal has entered a stage where the prime minister's responsibility is questioned.
The doctored documents related to the 2016 sale of state land to a school operator in Osaka at one-seventh of its appraised price with the alleged involvement of first lady Akie Abe, who supported the school's ultra-nationalistic education policy.
Aso blamed the alterations on "some staff members" at the ministry, and said he had only learned about them on Sunday.
The Moritomo scandal, which first surfaced in February previous year and pushed down Abe's support ratings, has drawn fresh attention after a major daily reported on March 2 that the ministry's documents had been doctored to remove descriptions saying the dramatically cut land sales price was "exceptional". Also removed was a reference to ties by Abe and Aso to a conservative lobby group, Nippon Kaigi.
Moritomo Gakuen's existing kindergarten attracted attention for requiring its young pupils to bow before portraits of the imperial family, sing the national anthem daily, and learn the 1890 imperial rescript on education, which emphasises sacrifice for country.
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The records include a comment from Yasunori Kagoike, the former head of Moritomo Gakuen, citing Akie Abe as telling him: "This is good land so please proceed". He said there was no "smoking gun" showing direct intervention by Abe or his wife.
Aso said the documents were doctored to be "coherent" with a speech made in parliament by the head of the tax agency Nobuhisa Sagawa, who stepped down on Friday over the scandal.
Sagawa headed the ministry division that submitted the documents before he was tapped as tax agency chief in July, an appointment critics saw as a reward for his efforts to diffuse the issue with his statements to parliament in 2017.
But they were essentially the same as documents made available to lawmakers previous year, and the ministry refused to clarify whether the papers had been altered as reported by The Asahi Shimbun.
The senior Liberal Democratic Party member said 14 of the original documents were rewritten by the ministry after the revelation of the scandal in February past year.
His ruling bloc won a two-thirds "super majority" in an October lower house poll, helped by opposition disarray.
A March 9 to March 11 survey by the Yomiuri newspaper showed support for Abe's cabinet has now fallen to 48 per cent, down six points from a month earlier.