Ruling People Power Party(PPP) interim chief Han Dong-hoon has stressed the need for the Corruption Investigation Office for High-ranking Officials(CIO) to swiftly investigate South Korean Ambassador to Australia Lee Jong-sup if it truly believes there is a problem. 

Han made the remark in Daegu on Thursday as he said if no preparations are in place to probe Lee, this would mean the CIO and the main opposition Democratic Party have engaged in politicking. 

Han said the PPP had Lee return to South Korea at the risk of diplomatic discourtesy before criticizing the CIO for resorting to messy media play ahead of important elections. 

The interim chief said the CIO has made no preparations to question Lee, adding that the agency must now provide an answer. 

Lee arrived in Seoul earlier in the day to attend a government meeting next week. 

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