SEOUL, The campaign of Rep. Ahn Cheol-soo, a leading contender in the ruling People Power Party (PPP)'s leadership race, said Tuesday it will file a complaint against a senior presidential secretary following revelations that presidential staffers campaigned for Ahn's leading rival.

Unidentified officials at the office of presidential secretary for civil society have been accused of rallying support for the front-runner, Rep. Kim Gi-hyeon, while discouraging support for Ahn, in a mobile chat room with party members.

Ahn's campaign said it plans to file a complaint against Kang Seung-kyoo, the senior presidential secretary for civil society, with the Corruption Investigation Office for High-ranking Officials over the case.

The accusations came as a four-day vote has been under way to elect a new leader of the ruling party since Saturday. The winner, unless a runoff vote takes place, will be announced Wednesday at the party's national convention.

Kim and Ahn are considered the two top candidates in the leadership race, though Kim is leading the race by a wide margin, according to recent opinion polls. Kim is widely believed to be President Yoon Suk Yeol's favorite.

"I think it was harder than running for president in some way ... I didn't imagine officials at the presidential office will interfere with the national convention like this," Ahn said in a radio interview, saying he will uncover the truth.

Ahn, however, said he does not believe President Yoon would have been involved in the matter.

The remaining two candidates in the PPP leadership race, former Prime Minister Hwang Kyo-ahn and lawyer Chun Ha-ram, have also raised concerns over the situation.

Source: Yonhap News Agency