Abe, whose high approval ratings have taken a hit, has repeatedly denied giving Kagoike money and on more than one occasion offered to resign if he was found to be involved in the land deal.

On Friday he issued a fresh denial, releasing emails between the first lady and Kagoike’s wife.

“There is nothing at all like a one million yen transaction mentioned in the exchanges,” Abe told parliament, referring to the emails.

“I disclosed all the emails to quash any misunderstandings,” Abe said, blaming Kagoike for disclosing “only part of the information” during his sworn testimony.

Analysts say such a donation in itself is unlikely to be illegal, but if proven could damage the prime minister’s credibility given his steadfast denials.

Abe also denied putting political pressure on bureaucrats to favour Kagoike when he purchased the state land for his now scuttled plan to construct a primary school.

The scandal has drawn intense interest in Japan largely due to the character of Kagoike, whose views on education are widely out of step with mainstream society.

He operates a kindergarten in the western city of Osaka that promotes hyper-nationalistic doctrine similar to that taught through the end of second world war.

The prime minister also rejected calls by opposition parties that his wife be summoned for questioning.

But newspapers supported the move.

“We need more testimonies” from bureaucrats, politicians and Abe’s wife, leading business daily Nikkei said in an editorial.

The scandal has put a significant dent in Abe’s approval ratings. His support level has fallen 10 points in recent weeks, the largest decline since he took office at the end of 2012. However, it still stands at a relatively healthy 56 per cent, according to the latest poll from the conservative Yomiuri Shimbun.