The presidential office Cheong Wa Dae on Friday said a special inspector's alleged leak of information over his probe into a presidential aide would constitute a "grave violation of the law," if it turns out to be true.

The remarks came a day after Lee Seok-su, a special inspector looking into the allegations of corruption involving Woo Byung-woo, senior presidential secretary for civil affairs, submitted a petition with the state prosecutors' office to seek a formal investigation.

Lee himself has been mired in a controversy after local broadcaster MBC reported Tuesday that he illegally leaked information about his investigation into Woo to an unspecified reporter via social media.

By law, a special inspector can face a prison sentence of up to five years for leaking information related to ongoing work.

"(The alleged leak of information, if it is true) is a grave breach of the law, and a matter that can't be condoned," senior presidential secretary for public affairs Kim Sung-woo told reporters.

According to the MBC report, the special inspector told a reporter that should Woo refuse to budge from his denial of all allegations against him, Lee would refer Woo's case to the prosecution.

Lee's special inspection began on July 21 amid mounting calls for Woo to step down.

Opposition lawmakers have even called for a special probe by an independent prosecutor into Woo's case.

Woo is alleged to have received favors from a disgraced former prosecutor in a 2011 real estate transaction involving the family of Woo’s wife.

He is also purported to have peddled influence to help his son get an easy job during his ongoing military service.

Another allegation against him is that he had misappropriated funds from a company run by his family. (Yonhap)