Prime Minister Shinzo Abe rejected more calls from the opposition Monday for his wife, Akie, to testify before the Diet over whether she offered a ¥1 million donation to Osaka-based private school operator Moritomo Gakuen, saying it was unnecessary.

"The issue of Moritomo Gakuen involves Mrs. Akie. She should appear before the Diet," said Yuko Mori of the Liberal Party, a small opposition party. The larger Democratic Party called for similar testimony last week.

Politically, the prime minister still does not appear vulnerable, as recent polls by major media outlets show his support rate is still over 50 percent, although a Kyodo poll over the weekend showed that more than half of the respondents thought Akie Abe should be invited to speak to the Diet, and that 62 percent were dissatisfied with either her or her husband's denials about being involved.