Cho Kuk, second from left, leader of the new Rebuilding Korea Party, speaks during a press conference held in front of the Supreme Prosecutors' Office in Seoul, April 11. Yonhap

A disgraced former justice minister called Thursday for investigations into allegations surrounding first lady Kim Keon Hee, as his one-month-old party had a surprise win in the parliamentary elections.

Cho Kuk, the leader of the new Rebuilding Korea Party, made the call after his minor party secured 12 proportional seats — the third-largest political party in the 300-member parliament — in Wednesday's parliamentary elections with a campaign pledge to put an early end to the conservative Yoon Suk Yeol government.

"(We) urge prosecutors to immediately summon President Yoon Suk Yeol's wife, Kim Keon Hee, to investigate (allegations surrounding her)," Cho said in a press briefing in front of the Supreme Prosecutors' Office in southern Seoul. "This is the order of people and the last warning to prosecutors."

Kim has been accused of involvement in manipulating the stock prices of Deutsch Motors, a BMW car dealer in Korea, between 2009 and 2012.

The main opposition Democratic Party of Korea railroaded a special investigation proposal to look into related allegations, but Yoon vetoed the bill in January. Kim has denied the allegations, but other people involved in the case were found guilty of stock manipulation charges.

The first lady also came under fire for receiving a luxury Dior handbag from a left-wing pastor in 2022, which was captured on a hidden camera and disclosed by local media in January.

During a media interview in February, Yoon said his wife failed to "coldheartedly reject" the gift giver but the stopped short of offering an apology.

Cho pressured prosecutors to launch investigations into Kim to address lingering concerns over the first lady's potential conflicts of interest and ethical standards.

"If prosecutors don't follow people's order, we will push for a special probe proposal on Kim as soon as the National Assembly opens after consultation with the Democratic Party of Korea," Cho said.

Cho, a former prominent law professor at Seoul National University, had served as the senior presidential secretary for civil affairs from 2017 to 2019 under the preceding Moon Jae-in administration. As one of Moon's closest aides, Cho was subsequently appointed as justice minister in September 2019.

However, he resigned in disgrace about a month later following an investigation into an academic fraud case involving his children, when Yoon was prosecutor-general.

Cho was convicted of academic fraud in connection with his daughter's college admissions and unlawful interference with a separate government inspection. In February, an appeals court upheld a two-year prison sentence for Cho.

A final guilty verdict could strip Cho of the parliamentary seat. (Yonhap)