Liberal politicians stepped up calls Friday for former President Lee Myung-bak to face justice amid a widening probe into allegations that the spy agency and military meddled in politics during his term from 2008-2013.

Prosecutors requested a warrant to arrest former Defense Minister Kim Kwan-jin on Wednesday over his possible link to the cyberwarfare command's online activities allegedly aimed at swaying public opinion in favor of the conservative government of the time.

The inquiry into the former defense chief has raised speculation that Lee, the former commander-in-chief, might also be involved in the political maneuvering scheme, either directly or indirectly.

"The prosecution has to directly investigate former President Lee and bring him to the court of history," Kim Dong-cheol, the floor leader of the main opposition People's Party, said during a party meeting.

"If prosecutors hesitate to address the past ills, our party will seek to shore up justice by enacting an independent counsel probe into the scandal," he added.

The National Intelligence Service and cyberwarfare command have been suspected of mobilizing operatives to post online comments to help shape public opinion in favor of the former conservative government, in apparent breach of rules on political neutrality.

The push for a probe into the scandal comes as the liberal Moon Jae-in government conducts sweeping reforms under the name of "eliminating accumulated ills." But conservatives have dismissed the endeavors as "political retribution."

Choo Mi-ae, the leader of the ruling Democratic Party, sharpened her rhetoric against Lee.

"(The alleged political interference) was a breach of national order and a case that trampled upon the constitutional order," she said during a party meeting. "What Lee should do first is to repent and make a candid confession for the future of our nation."

Lee has reportedly criticized the prosecution for burrowing into issues from a bygone era, saying, "The nation is bound by the past."

In a Facebook post in September, Lee chafed at the Moon government's campaign to redress alleged wrongdoings of past governments, saying that it would not only compromise national interests, but also end in failure. (Yonhap)