A group of lawyers led by Hidetoshi Masunaga filed lawsuits with the Fukuoka High Court and elsewhere on Monday morning to nullify the results of previous day's general election for the House of Representatives.

The group seeks to invalidate the election results for all single-seat constituencies of the lower chamber of parliament, saying that the poll was unconstitutional because it was carried out without correcting vote-value disparities.

Separately, some members of the group and a team of other lawyers, including Kuniaki Yamaguchi, were set to file similar suits later in the day.

"Elections provide the only venue where citizens can engage in the exercise of state power," lawyer Takanori Hirai told a news conference in Fukuoka Prefecture after the filing.

"I wonder if (Sunday's poll) was a legitimate election,"

Hirai said, mentioning that the law to establish a council for rezoning electoral districts stipulates that vote-value gaps be kept below 2 times.

According to the internal affairs ministry, the No. 3 constituency of Hokkaido had the highest number of voters the day before the Oct. 15 candidacy registrations, with 461,457 voters. Meanwhile, the No. 1 constituency of Tottori Prefecture had the lowest number with 224,060 voters.

The vote-value gap between the two districts is estimated at 2.06 times, slightly lower than the maximum gap of 2.08 times in the previous Lower House election in 2021.

Japan enforced in December 2022 the revised public offices election law to rezone Lower House single-seat constituencies in order to reduce vote-value gaps.

Following the rezoning, the maximum gap fell below 2 times based on 2020 census data. But it later rose above the level.

The plaintiffs argue that Sunday's election violated the Constitution's requirement for equal value in votes.