NHK has learned that Tokyo prosecutors have begun questioning lawmakers of the main ruling Liberal Democratic Party in connection with a political funds scandal.

The LDP's largest faction once led by the late Prime Minister Abe Shinzo is suspected of not having reported some of revenues from fund-raising parties in its political funds report.

The Abe faction is also suspected of treating the unreported money as slush funds in a systematic way.

Most lawmakers belonging to the Abe faction, including six senior lawmakers, allegedly received some of the profits from ticket sales for the group's fund-raising events as kickbacks.

The kickbacks are believed to have amounted to about 500 million yen, or about 3.5 million dollars, over a five-year period through last year.

Sources tell NHK that Tokyo prosecutors have already begun questioning lawmakers of the Abe faction on a voluntary basis.

The prosecutors plan to question dozens of other lawmakers about their knowledge of the practice and how they became involved in it.