Opposition lawmakers on Wednesday ratcheted up calls for beleaguered Justice Minister Katsutoshi Kaneda to step down amid allegations he sought to stifle Diet debates on a contentious anti-conspiracy bill by manipulating media.

At the heart of the furor is an unprecedented statement distributed to Japanese media at the urging of Kaneda on Monday suggesting that any Diet debate on the proposed legal revision to make conspiracy to commit terrorism a criminal offense should be withheld until the amendment is officially submitted to the current legislative session.

Lawmakers from the main opposition Democratic Party denounced the statement as an attempt to "manipulate" the perception of the amendment and called for Kaneda's resignation, citing his lack of qualification for the post.