Military investigators are considering indicting about 20 of the cyber warfare command's officials on charges of engaging in an alleged smear campaign against the opposition candidate during last year's presidential election, sources familiar with the matter said Tuesday.

The ministry has been looking into the cyber command the past two months after some members of its psychological warfare unit were caught posting political messages against the opposition camp ahead of the December election.

Some cyber warfare officials allegedly posted or spread writings on social networking sites such as Twitter that were critical of then-presidential candidate Moon Jae-in of the Democratic Party (DP) in violation of their obligation to stay politically neutral.

After investigating all officials in charge of psychological warfare over the alleged smear campaign, the military investigation team has picked out about 20 officials subject to legal punishment.

"The Central Investigation Command will announce an interim result that asks state prosecutors to indict 20 psychological warfare officials without arrest," a senior military official said, asking for anonymity. "Military prosecutors will further investigate those involved to decide the level of legal punishment."

In South Korea, prosecutors have the exclusive right to make indictments.

Among them are the director of the psychological warfare unit and some key officials for violating military standing orders stipulating political neutrality. The defense minister and the head of the cyber command were not on the list.

The team is expected to announce the result between Wednesday and Thursday, ministry officials said.

On Tuesday, the Democratic Party (DP) raised fresh allegations that the psychological warfare unit's activities had been reported to Defense Minister Kim Kwan-jin and the presidential office, urging Kim to step down and launch an independent investigation council led by a special prosecutor.

Ministry spokesman Kim Min-seok refuted Kim's involvement in the online smear campaign, saying the psychological warfare unit's briefings were related to North Korea's cyber attacks, infiltration attempts and online activities.

The cyber command was created in 2010 to counter North Korean hacking attempts in light of growing security threats in cyber space. (Yonhap News)