Abe, now in his sixth year in office, had tried to put behind him questions over the sale of state-owned land at a huge discount to a school operator with ties to his wife, Akie, behind him. His ratings had rebounded from a slump last year, but doubts have revived with a series of fresh revelations.
Abe has repeatedly denied he or his wife did favours for school operator Moritomo Gakuen, which bought the land, and has said he would resign if evidence were found that they had. The issue last year sharply eroded Abe’s popularity.
Suspicions of a cover-up could slash Abe’s ratings and dash his hopes of a third term as leader of the ruling Liberal Democratic Party (LDP). Victory in the LDP September leadership vote would put him on track to become Japan’s longest-serving premier. The doubts have also sparked calls for Aso to resign.
A March 9-11 survey by the Yomiuri newspaper showed support for Abe’s cabinet fell to 48 percent, down six points from a month earlier. Non-support rose to 42 percent and 80 percent said that the matter had not been handled appropriately.
LDP parliamentary affairs official Hiroshi Moriyama told reporters that he had been briefed by finance ministry officials that the documents related to the land sale had been altered.
Media have said the changes were made after February last year – when the suspected scandal broke – and that words describing the “special nature” of the deal were excised along with the names of several politicians.
“If this is true, isn’t political responsibility unavoidable?” said Akira Nagatsuma, a senior lawmaker in the opposition Constitutional Democratic Party of Japan, on Sunday.
Former Moritomo Gakuen head Yasunori Kagoike and his wife were arrested in July on suspicion of illegally receiving subsidies.
On Friday, National Tax Agency chief Nobuhisa Sagawa abruptly resigned over his remarks in parliament about the case.
Also on Friday, media said police were investigating as possible suicide the death of a finance ministry official whose local office had handled the land sale.
“If Minister Aso signed off on National Tax Agency chief Sagawa’s resignation knowing about the falsified documents, moves seeking his resignation are inevitable,” Yuichiro Tamaki, leader of the opposition Democratic Party, said on Sunday.
Some LDP members also suggested politicians had ultimate responsibility.
“It is inconceivable that the bureaucrats on the spot had such authority (to alter the documents),” media quoted Shigeru Ishiba, an LDP lawmaker who has made no secret of his desire to challenge Abe in the party race, as saying on the weekend. “If we don’t make clear who did this, trust in the LDP will waver.”
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 last year.
Aso and Abe have both defended the appointment as “appropriate” and Aso has said he will not resign.
Abe, 63, swept back to power in December 2012 promising to revive the economy and bolster its defence.
It was a rare comeback for the conservative lawmaker, who quit abruptly in 2007 after a year in office marked by scandals in his cabinet, a deadlocked parliament and ill health.
His ruling bloc won a two-thirds “super majority” in a October lower house poll, helped by opposition disarray.