After coming under renewed attack from opposition parties, Prime Minister Yoshiro Mori admitted Sunday that a remark he made the previous day using the term "kokutai" was improper.

The word refers to a national polity centering on the Emperor before and during the World War II.

"Last night in Nara, I spoke too long . . . made a slip of the tongue and have been scolded again," Mori said during a lecture in Matsue, Shimane Prefecture.

The apparent attempt to quell growing antipathy among voters came after all four major opposition parties launched a fresh attack on the 62-year-old prime minister, who remains tainted by an earlier comment in which he described Japan as a "divine nation centering on the Emperor."