It was customary for past Japanese prime ministers to distribute gift certificates, Liberal Democratic Party lawmaker Shoji Maitachi said Sunday.

"It's something prime ministers have routinely done as a custom," Maitachi told an LDP prefectural chapter meeting in Tottori Prefecture's namesake capital in western Japan.

Maitachi, a member of the House of Councilors, the upper chamber of the country's parliament, made the remark as Prime Minister Shigeru Ishiba is under fire for giving gift certificates worth ¥100,000 each to lawmakers newly elected to the House of Representatives, the lower chamber, last year.

Opposition lawmakers say that the practice appears to be a violation of the political funds control law, which bans donations to support political activities.

At the meeting, Maitachi offered apologies over the scandal, saying that the ruling party must accept criticism that the practice is far removed from common sense, especially when the public is suffering from rising prices.

Maitachi, a former internal affairs ministry official, is a member of the Tottori chapter as is Ishiba.

Speaking to reporters in the northeastern city of Aomori on Sunday, Constitutional Democratic Party of Japan leader Yoshihiko Noda said that Ishiba should testify about the scandal before a parliamentary political ethics panels. Democratic Party for the People's head, Yuichiro Tamaki, expressed a similar view on television.