Prosecutors said Monday they will launch an investigation into allegations two former lawmakers, including a key member of ruling party presidential candidate Park Geun-hye's primary campaign team, took tens of millions of won in illegal political funds and bribes ahead of April's parliamentary elections.

Former Rep. Hong Sa-duk of the ruling Saenuri Party is accused of receiving a total of 60 million won ($53,690) in illegal political funds from a businessman between last autumn and March of this year, according to the country's election watchdog, which reported the case to the prosecution earlier in the day.

Hong, who formerly served as co-chairman of Park's election campaign committee during the ruling party's presidential primary, immediately denied the bribery suspicions.

The National Election Commission also said former Rep. Jang Hyang-sook of the main opposition Democratic United Party is suspected of accepting 33 million won early this year from an unidentified person who allegedly asked for her help in securing a proportional representative ticket in April's election.

"(The NEC) filed the case with us this morning and we started to review it in the afternoon," said an official at the Supreme Prosecutors' Office. "We plan to assign the case tomorrow morning."

The new probe will join a number of ongoing investigations involving ruling and opposition party members who are suspected of exchanging money for favors.

Rep. Hyun Young-hee, now an independent after recently being expelled from Saenuri, is accused of giving 300 million won to members of the party's nomination committee in return for securing a proportional representative ticket in the elections.

DUP floor leader Park Jie-won is suspected of taking bribes from an ailing savings bank seeking to avoid regulatory audits and punishment. (Yonhap News)