NHK has learned that the offices of two more senior lawmakers of Japan's main ruling Liberal Democratic Party may have received kickbacks from selling tickets for political fundraising parties.

The largest LDP faction, the Seiwa policy study group, is believed to have paid kickbacks to its member lawmakers who exceeded their ticket sale quotas. It is accused of failing to declare the extra income and the payouts to lawmakers as expenditures in its political fund reports. The faction was once led by late Prime Minister Abe Shinzo.

Sources say the offices of Diet Affairs Chief Takagi Tsuyoshi -- the faction's general secretary -- and LDP Upper House Secretary General Seko Hiroshige allegedly received kickbacks but failed to enter the income in their reports.

The kickbacks paid to the offices are estimated to have topped 10 million yen, or 69,000 dollars, each over the five-year period through the end of 2022.

It has already come to light that the office of Chief Cabinet Secretary Matsuno Hirokazu, a senior member of the faction, received kickbacks totaling 69,000 dollars over the same period and failed to report the income in its reports.

The total amount of the kickbacks to lawmakers of the faction is estimated at several million dollars.

Tokyo prosecutors are believed to be considering questioning lawmakers on a voluntary basis, and unraveling the concealed flow of funds.