The defense ministry will announce this week the interim result of an investigation into the cyber warfare command over its alleged online smear campaign in last year's presidential election, military officials said Wednesday.

The announcement, scheduled for Thursday, coincides with the one-year mark of last December's election in which the then ruling party candidate, Park Geun-hye, won a tight race against the opposition Democratic Party candidate, Moon Jae-in. Park was sworn into office in February.

The country's rival parties have since been engaged in a prolonged political hassle over the election meddling scandal that also allegedly involves the state spy agency and other government agencies.

The ministry has been looking into the cyber command in the past two months after some members of the command's 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 Moon, failing to uphold their duty as public officials to maintain political neutrality.

After investigating all officials in charge of the

psychological warfare unit over the alleged smear campaign, the military investigation team has picked out the psychological warfare unit director and some 20 key officials, subject to legal punishment, according to a source familiar with the matter.

The defense minister and the head of the cyber command were not on the list, while lower-level officials involved in the case are likely to face disciplinary actions, the source said.

Once the investigation is completed, the military is expected to hand over those involved to prosecutors for indictment without arrest.

The interim result, however, is not likely to satisfy opposition lawmakers who claim the military joined hands with the state spy agency to systematically carry out an online smear campaign under a seemingly larger election meddling scheme, along with other government bodies.

The former chief of the National Intelligence Service is currently undergoing trials on charges of election meddling.

On Tuesday, DP lawmakers belonging to the parliamentary legislation committee issued a statement criticizing the military's ongoing investigation and called for an independent counsel to launch a thorough investigation.

  "It is doubtful that the psychological warfare unit director has masterminded (the online smear campaign)," the statement said. "The military is trying to cover the sky with its hands to give immunity to the cyber warfare command (under the defense ministry)."

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