Amid criticisms surrounding his appointment, South Korean Ambassador to Australia Lee Jong-sup is set to visit Seoul to attend a conference with the heads of South Korean diplomatic missions in six countries, starting Monday.

Officials confirmed Lee's planned participation in next week's inter-ministerial conference, which will be attended by South Korean ambassadors stationed in partner countries of Seoul's defense industrial cooperation, including Australia.

The visit is taking place at the height of the ongoing controversy over the former defense minister's appointment, which came despite a pending investigation over his alleged interference in a probe into the death of a Marine during a search and rescue operation last year.

In a statement through his lawyer on Tuesday, Lee submitted a letter urging the Corruption Investigation Office for High-ranking Officials(CIO) to swiftly set a date to question him in connection with the probe.

Lee is returning to Seoul just two weeks after taking office.