South Korea’s Ambassador to Australia and ex-Defense Minister Lee Jong-sup returned home Thursday as the rival parties here called for a tougher investigation into his alleged manipulation of a military probe into the death of a young marine last year.

Lee landed in Korea via Incheon International Airport in the morning, 11 days after he flew to Australia to assume his role as top envoy to Australia. The departure on March 10 came two days after the Justice Ministry lifted Lee’s travel ban, despite the state-affiliated anti-corruption agency’s ongoing investigation into the former defense minister.

Upon arriving at the airport, Lee told reporters that he plans to cooperate with the Corruption Investigation Office for High-ranking Officials.

"I hope to be able to coordinate a schedule with the CIO so that there is an opportunity to attend questioning during my stay," he said.

At the same time, he denied the accusations that he played a key part in delaying the probe into the death of Cpl. Chae Su-geun, who was killed in July last year after being swept away by a strong current during a search and rescue mission for victims of a heavy downpour.

“I have clearly stated multiple times that the various allegations made against me are not true,” Lee told reporters.

The foreign ministry said in a release that a meeting of chiefs of six diplomatic missions will take place in Seoul on Monday.

Lee added that he came to Korea to attend the meeting of chiefs to discuss defense cooperation among the countries. The six countries are: Australia, Indonesia, Poland, Qatar, Saudi Arabia and the United Arab Emirates, according to the Foreign Ministry’s earlier statement.

The ruling People Power Party and the main opposition Democratic Party of Korea on Thursday displayed rare bipartisan coordination in adopting a hardline stance towards the scandal surrounding Lee.

The People Power Party, which usually supports the Yoon Suk Yeol Cabinet’s decisions, had called for the swift return of Lee in recent weeks, as critics interpreted the scandal as a risk that could weigh down the ruling party ahead of the April 10 legislative election.

People Power Party Rep. Kim Tae-ho, a three-term lawmaker and a candidate for the upcoming election, voiced the need for Lee’s resignation and a “thorough investigation.”

“Ambassador Lee must immediately resign and be investigated (by the CIO after being stripped of his current privileges),” Kim said in a Thursday post uploaded on Facebook.

“(If Lee doesn’t act confident regarding the investigation), we will become a frequent target of (the main opposition’s) narrative of bringing judgment towards the current administration as we head towards the election,” he added.

Democratic Party Chair Lee Jae-myung echoed Kim by also calling for Lee’s immediate resignation and warned to propose several investigation bills into the scandal.

“President Yoon must immediately remove Lee from his current position (as the top envoy to Australia) and implement another travel ban on him,” Lee said during a party event in the country’s southwestern city of Gwangju.

“We strongly ask the People Power Party to (cooperate) in our plan to propose investigations into (Lee and Cpl. Chae’s death).”

Early in the day, several Democratic Party lawmakers gathered in front of the Incheon airport terminal, holding placards criticizing Lee, as they waited for the top envoy's arrival.