Defiant Abe hits back over scandal as support plunges

Japan's embattled prime minister hit back today at critics over a favouritism and cover-up scandal that has seen his popularity plunge and loosened his iron grip on power.

In a hotly awaited statement in parliament, Shinzo Abe stressed he had not ordered bureaucrats to alter documents relating to a controversial land sale as he comes under mounting pressure over the scandal.

"I have never ordered changes," he said.

The scandal surrounds the 2016 sale of state-owned land to a nationalist operator of schools who claims ties to Abe and his wife Akie.

The sale was clinched at a price well below market value amid allegations that the high-level connections helped grease the deal.

The affair first emerged early last year, but resurfaced after the revelation that official documents related to the sale had been changed.

Versions of the original and doctored documents made public by opposition lawmakers appeared to show passing references to Abe were scrubbed, along with several references to his wife Akie and Finance Minister Taro Aso.

Aso has blamed the alterations on "some staff members" at the ministry.

The prime minister repeated an apology saying he "keenly felt" his responsibility over the scandal that has "shaken people's confidence in government administration."