Complaints filed against South Korean Ambassador to Australia Lee Jong-sup, who's suspected of interfering in an investigation related to the death of a young Marine last year, have been assigned to the anti-corruption body's investigation team.

According to the Corruption Investigation Office for High-ranking Officials(CIO) on Wednesday, the investigation comes as a civic group known as the National Action for Judicial Justice, the National Innovation Party and the Green Justice Party all filed complaints against President Yoon Suk Yeol, justice minister Park Sung-jae and foreign minister Cho Tae-yul. The complaints were filed after Lee's overseas travel ban was lifted.

The CIO announced Tuesday that additional questioning is necessary for the diplomat over his suspected abuse of power in a case related to the death of a young Marine last summer.

The complaints filed center on the premise that the defense minister-turned-diplomat was wrongly assigned to his new post and his overseas travel ban was lifted in order to cover up the charges he's facing, despite the ongoing CIO probe.

His overseas travel ban was lifted by the justice ministry a day after he was questioned for four hours last Thursday, before departing for Australia this past Sunday.