A MBC reporter talks to South Korea's ambassador to Australia and former Defense Minister Lee Jong-sup, at the Brisbane Airport in Australia on March 10. (Yonhap)

A dispute over the Yoon Suk Yeol administration’s recent decision to greenlight the lifting of the travel ban on South Korea's new ambassador to Australia intensified Monday, as the ruling party chief and the state-affiliated corruption investigation agency expressed their disapproval of the move.

The latest conflict follows the Justice Ministry’s decision earlier this month to allow the departure of the recently appointed envoy and former Defense Minister Lee Jong-sup to Australia on March 10, despite an ongoing investigation into the ex-minister.

Lee has been accused of meddling in the investigation of the death of Cpl. Chae Su-geun, who died in July last year after being swept away by a current during a civilian search and rescue mission amid heavy rain and flooding.

The presidential office on Monday reiterated the Justice Ministry’s earlier explanation that they had no reason to retain Lee’s travel ban as the Corruption Investigation Office For High-ranking Officials failed to subpoena Lee after a relevant complaint was filed with the state-affiliated probe agency in September last year. The travel ban against Lee had been extended multiple times throughout the CIO’s investigation period despite the lack of a subpoena, it added.

“It is highly inappropriate for the chief of an overseas mission to return home and wait indefinitely when the CIO has yet to summon him over their lack of preparedness for an investigation,” the presidential office said in the notice to the press.

"Ambassador Lee is ready to respond immediately at any time to the CIO’s subpoena requests. Lee was officially appointed as envoy to Australia following not only the Justice Ministry’s approval to lift his travel ban, but the CIO’s approval to greenlight his overseas travel,” it added.

The CIO however soon contradicted the statement by denying that it gave consent to Lee’s departure.

“We maintain our initial stance that it is difficult to confirm the progress of the investigation, but there is a part of the presidential office’s statement (that we would like to clarify),” it said.

“We do not have the authority to lift travel bans on our subjects of the probe and have not allowed the departure of the subject during the investigation process.”

The CIO added that it submitted its opinion to the Justice Ministry that Lee's travel ban should be retained.

Meanwhile, growing public flak over the Yoon administration’s decision opened another round of disagreement between the president and the ruling People Power Party Interim Chair Han Dong-hoon, ahead of the April 10 general election.

Han on Sunday called for the authorities to summon Lee back to Korea immediately to allow the CIO to complete its investigation.

"The CIO has to subpoena (Lee) immediately and the ambassador has to return at once," Han told reporters at the party headquarters in western Seoul.

"I don't think this should even be a topic of political bickering ahead of the elections, as it would only cause distress (among) the people,” he added.

Whether he expressed his opinion on summoning Lee to the presidential office, Han replied that he had “sufficiently” done that.

Critics say that Han was reacting to Yoon's plummeting approval rate after his administration approved of Lee's departure to Australia.

Yoon’s approval rate fell 1.6 percentage points on-week to 38.6 percent in the third week of March, according to a Real Meter poll released Monday. The local pollster cited the lifting of Lee's travel ban as a key factor behind his decline in popularity.

The latest fissure between Yoon and Han follows their first round of rift observed in January prompted by their differences over how to handle allegations that first lady Kim Keon Hee abused anti-graft laws by receiving a luxury handbag as a gift in 2022.

In response to the snowballing controversy, Lee said he "could return even tomorrow if the CIO subpoenas him," in a late Sunday video interview with KBS. His meeting with the CIO officials is scheduled to take place in late April, Lee added.

When asked about the conflict surrounding Lee, the Australian Embassy in Korea replied "Australia values our important relationship with (South Korea) and looks forward to working with Ambassador Lee in his new role," via e-mail.