The main opposition Democratic Unity Party has decided to launch an investigation into allegations of a bribery that took place prior to a preliminary primary last month, a party spokesman said Monday.

The move came hours after local media reported that some officials of a candidate allegedly gave money worth up to 500,000 won ($430) over a dinner to some regional heads of the party.

Last month, the newly created party selected a former prime minister and eight other candidates who will run in a new leadership race set for Jan. 15.

"We decided to immediately form a fact-finding team to thoroughly grasp the facts," party spokesman Oh Jong-sik said. He said the party will strip a candidate of the right to run in the leadership race and ask the prosecution to launch an investigation if irregularities are found.

The opposition party said it still plans to go ahead with a convention on Sunday to elect new leaders.

(Yonhap News)