NHK has learned that Tokyo prosecutors have questioned another high-ranking member of the main ruling Liberal Democratic Party on a voluntary basis in connection with a political fundraising scandal.

Nikai Toshihiro is a former secretary-general of the LDP, and heads the party's Nikai faction. The faction is said to have paid kickbacks to the offices of member lawmakers who sold tickets for fundraising events in excess of their quotas.

It has also been revealed that the offices of some lawmakers kept the excess revenues after selling the tickets, without handing them over to the faction.

Nikai's office is believed to be among those that held on to the funds, in the five years through 2022.

Neither the faction, nor the offices of the lawmakers concerned, are said to have reported the extra revenues in their political funding reports -- an action that would violate the law.

The office of the Nikai faction was raided last month on suspicion of violating the political funds control law.

Prosecutors also searched the office of the faction once led by the late Prime Minister Abe Shinzo over similar allegations. Senior members of the Abe faction have also been questioned on a voluntary basis.

Nikai had issued a statement following the raid, offering his apologies for causing trouble and concern. He said his faction will cooperate with prosecutors in good faith.