In a meeting with House of Councillors President Satsuki Eda, who hails from the DPJ, Aso said Germany had precipitated a tragedy "after deciding to let the Nazis assume power at one time," according to participants at the meeting.

DPJ Secretary General Yukio Hatoyama called the remark "an intolerably abusive statement" and demanded that Aso, the LDP's new No. 2 leader after Prime Minister Yasuo Fukuda, withdraw it.

"The DPJ won a sweeping victory in last year's upper house election. But does it aim to win power?" Aso was quoted as saying to Eda. "If so, the DPJ needs to act in a more responsible manner."

The DPJ-led opposition camp, which controls the upper house, can block bills that have passed the House of Representatives in which the LDP and its coalition partner, the New Komeito party, hold a comfortable majority.

"The public voted for the Nazis," Aso was quoted as saying, while Eda responded that people today would "not make such an unreasonable choice. I don't think the public see the DPJ in such a way."

Aso later told reporters that he did not mean to liken the DPJ to the Nazis, saying, "I only said it is important to deliberate matters seriously in the upper house" out of concern that being negligent in such talks could allow the emergence of forces like the Nazis.

Hatoyama told reporters the DPJ finds it difficult to overlook Aso's comment. "In linking us to the Nazis, this remark could give the impression that if the DPJ assumes power it will embark upon oppressive politics."

Azuma Koshiishi, leader of the DPJ's upper house caucus, also questioned Aso's comment, saying, "Is it right for the secretary general of a governing party to say things that could be misunderstood?"