NHK has learned that five senior members of the Abe faction in Japan's main ruling Liberal Democratic Party have said they did not know that part of the revenues from fundraising parties were not recorded in the faction's political funds reports.

The Abe faction is suspected of having paid kickbacks to the offices of member lawmakers who sold tickets for fundraising events in excess of quotas without recording the extra revenue in its political funds reports.

Tokyo prosecutors have questioned, on a voluntary basis, five senior Abe faction members. They are former Chief Cabinet Secretary Matsuno Hirokazu, former LDP Diet Affairs Committee Chairperson Takagi Tsuyoshi, former LDP Upper House Secretary-General Seko Hiroshige, former education minister Shionoya Ryu and former LDP Policy Research Council Chairperson Hagiuda Koichi.

Sources say the five officials told the prosecutors that they were not involved in the faction's failure to report the excess revenue.

The sources say the five explained that they knew the amount exceeding the quota was refunded to the lawmakers' offices, but did not know the money was not listed in the faction's political funds reports.

The sources say the official in charge of the faction's accounting admitted to having failed to register the kickbacks. The official reportedly understood that such funds must be recorded in the reports.

Prosecutors are expected to hear from more lawmakers belonging to the faction.