A university professor filed a criminal complaint with prosecutors Wednesday against a former high-ranking bureaucrat and other officials, accusing them of improperly disposing of public documents pertaining to a shady state land sale linked to the wife of Prime Minister Shinzo Abe.

The complaint by Hiroshi Kamiwaki, a professor at Kobe Gakuin University, alleged that Nobuhisa Sagawa, who led the Finance Ministry's bureau in charge of the land deal, and other ministry officials had colluded to discard the records.

According to the complaint, Sagawa and the officials are alleged to have taken action to prevent the documents from falling into the hands of opposition lawmakers, who would have tied Abe's wife, Akie, to the transaction.

Such a development could result in the prime minister's resignation. Abe has repeatedly denied his or his wife's involvement in the apparent sweetheart deal.

The documents disposed of were part of the records of negotiations between ministry officials and school operator Moritomo Gakuen, which was offered a state-owned plot of land at less than a seventh of its appraised value.

After submitting the complaint to the Osaka District Public Prosecutors Office, Kamiwaki told reporters that if a criminal charge is not pursued it would encourage the state and politicians to "actively dispose of records that cast an unfavorable light on them," thus undermining democracy.

The prosecutors had also investigated Sagawa and others on suspicion of altering official documents, but are not pressing charges against them due to a lack of evidence, investigative sources said.

The ministry has admitted it disposed of and doctored documents to conceal negotiations with Moritomo Gakuen. It recovered some of the documents from officials who had personally kept copies, releasing last week over 900 pages of records from between 2013 and 2016.