Prosecutors said Monday they questioned an opposition lawmaker over allegations that he took part in helping the former Park Geun-hye government conduct an illegal election survey using the state spy agency's money.

Rep. Kim Jae-won of the Liberty Korea Party was summoned earlier in the day and has been undergoing an interrogation over the allegations, the Seoul Central District Prosecutors' Office said.

Kim is suspected of carrying out the survey intended to gauge public opinion in North Gyeongsang Province, including Daegu, the stronghold of the conservative bloc and the former president. 

Prosecutors believe that the National Intelligence Service paid the presidential office Cheong Wa Dae 500 million won ($460,000) for the survey.

They said they are focusing the probe on Kim to find out whether Park gave direct orders regarding the survey and the execution of the NIS fund.

Kim was then the senior presidential secretary for political affairs.

The prosecution has been widening its investigation into the suspected misappropriation of the NIS' off-book funds worth at least 3.3 billion won by its officials, including chiefs.

Nam jae-joon and Lee Byung-kee, two of the three NIS chiefs who served under Park's leadership, have been arrested over embezzlement, abuse of power and loss of state funds in connection with the scandal.

Prosecutors also asked opposition bigwig Choi Kyung-kwan of the same party to appear for questioning over similar allegations. He refused to appear for the summons, denying any wrongdoing. (Yonhap)