Rep. Choi Kyung-kwan of the Liberty Korea Party will be questioned by prosecutors next week as a suspect in a graft case in connection with the state spy agency, Seoul prosecutor's office said Thursday.

The Seoul Central District Prosecutors' Office said he will appear for interrogation next Tuesday.

Prosecutors raided his home and office at the National Assembly early this week to confiscate evidence.

They believe the money was paid to lobby him for retaining NIS off-the-book funds -- with which the spy agency allegedly paid Choi
-- when then opposition parties pushed for scaling it down on the basis of the untraceable nature of the "NIS special activities fund". He has denied any wrongdoing.

The raid is part of a far-reaching probe into a massive scandal at the NIS involving ousted President Park and her two aides.

Prosecutors have alleged that the NIS paid Park and her aides at least 3.3 billion won from its coffers, until months before she was forced out of office over an influence-peddling scandal. 

Two former NIS chiefs have been arrested for arranging the illegal payments. Lee Byung-kee, one of them, apparently told the prosecution that he approved the NIS payment to Choi when he was the director in October 2014. (Yonhap)