Two former cyber command chiefs have been charged with being involved in the posting of politically biased messages online by their subordinates before the 2012 presidential election, the defense ministry said Tuesday.

Yeon Jae-wook and Ok Do-kyung were among 21 former and current officials of the ministry's cyber command who are facing criminal charges "in violation of the military criminal act that stipulates their obligation to stay neutral."

Wrapping up its months-long probe into the allegations, the ministry said, "Beyond the bounds of normal operations, officials of the command's psychological warfare team made some 7,100 postings online in favor of or against specific political parties and politicians."

"Yeon and Ok are charged with aiding the political intervention by failing to taking proper actions even though they were notified of such illegal operations," the ministry said noting that their idling "led the officials to think that such politically biased expressions were allowed."

The scandal hit the country last year as allegations surfaced that the command, along with the state spy agency, tried to sway public opinion in favor of then ruling party candidate and now President Park Geun-hye through online posts ahead of the 2012 election.

Of the 21, the former director of the team, identified only by his surname Lee, has been on trial after being indicted for ordering his subordinates to post politically biased writings and destroy evidence.

Upon his instruction, 16 psychological warfare officials were found to have posted political comments on Twitter and blogs via cell phone and tablet PCs.

Two others were charged with destroying relevant evidence and writing false official documents, according to the ministry.

The results of the extensive probe, however, have led to controversy as the ministry concluded, "There were no organized attempts to meddle in the presidential election upon instructions by the military or outside entities and in connection with other government agencies, such as the National Intelligence Service."

The ministry also said then-Defense Minister Kim Kwan-jin, who now serves as the national security adviser, had been kept in the dark about the case, though he had been in charge of the cyber command.

Expressing regret over the incident, the ministry vowed to take reform measures to guarantee its political neutrality.

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