Kim held a late night press conference and denied the allegations.

The lawmaker admitted that there was contact with one of the party members in question, who expressed that he would voluntarily help him. But Kim said that he rejected the offer, which apparently caused the person to turn around to attack the government.

The LKP lashed out at Kim, saying that his explanation is full of excuses and urged him to immediately disclose his communication with the person.

"(His) excuses are so long and pathetic," said Chang Je-won, LKP spokesman, adding that his press conference must be aimed at thwarting media coverage of the case.

Chang also called on the prosecution to take swift action to secure relevant evidence so as to get to the bottom of the case.

The minor opposition Bareunmirae Party and the Party for Democracy and Peace have called for a thorough investigation into the case, comparing the case with opinion rigging attempts by the military's cyber warfare command and the state intelligence agency during previous conservative administrations.

Ahn Cheol-soo, a key member of the Bareunmirae Party, told reporters that, through Kim's explanation made during the press conference, Kim meant to portray himself as a victim, a tactic aimed at drawing attention away from the case.

"This is not an aberration by an individual but a conspiracy with organized crimes," he said, urging Kim to face the prosecutorial investigation.

The ruling party dismissed the accusations and related media reports as a "witch hunt" that lacks substantiated evidence or proof.

"We express our grave concern over the political circles and media reports suggesting that Kim was behind all of this," Baek Hye-ryun, a party spokesperson, said. (Yonhap)