TOKYO - Former Japanese Prime Minister Shinzo Abe submitted to voluntary questioning by Tokyo prosecutors on Monday in a case against his secretary over unreported political funds, public broadcaster NHK reported on Tuesday, citing unidentified sources.

Abe, who stepped down citing ill health in September, is under fire on suspicion his office helped cover the costs of dinner parties for supporters, a possible violation of funding laws that he denied when questioned in parliament last year.

Prosecutors have been building a case against Abe's secretary over unreported funds involving as much as 40 million yen ($386,922) and had asked Abe to appear for voluntary questioning about the issue, domestic media reported this month.

Tokyo prosecutors said they do not comment on investigations. Abe's office declined to comment and requested that questions be sent by facsimile.

The issue also risks hurting current Prime Minister Yoshihide Suga, who was Abe's right-hand man during his 2012-2020 tenure and defended him in parliament.

Suga has already seen his approval ratings tumble over his response to the COVID-19 pandemic. He drew fire for joining year-end social gatherings despite asking Japanese citizens to avoid such parties amid a surge in coronavirus cases. REUTERS