With Prime Minister Han Duck-soo carrying out the presidential duties of beleaguered President Yoon Suk Yeol, the ruling and the main opposition parties are clashing over the interim leader's rights regarding presidential veto and the appointment of Constitutional Court justices.

Rep. Lee Jae-myung, the leader of the main opposition Democratic Party of Korea, expressed regrets on Friday about Han exercising veto on the six bills recently passed unilaterally by the Democratic Party. The bills include a revision of the Grain Management Act, which would have obligated government intervention in case of rapidly changing rice prices.

Han and the ruling People Power Party said revising the grain law would lead to an excessive supply of grains and strain the government budget, while the main opposition decried it as a clear violation of the parliament's rights. The Democratic Party has warned of a push for Han's impeachment if he vetoes the bills, although it did not immediately announce plans for such action.

The two biggest parties of the National Assembly do not see eye-to-eye on the impeachment either, as the law does not specify the conditions for an interim leader's impeachment after Han's veto.

The ruling party has said that a minimum of two-thirds of the 300 lawmakers should approve the impeachment motion to be passed by the parliament -- equal to the requirement for a president's impeachment. But the main opposition has said the motion should be passed with just more than half of the National Assembly members' approval required for the impeachment of a prime minister-- which would be 151.

The Democratic Party currently has 170 seats in the National Assembly, while the ruling party has 108. This means the main opposition or the pan-opposition bloc could unilaterally pass an impeachment motion for a prime minister but requires the cooperation of at least a handful of ruling party members to get 200 votes.

While the matter is legally vague, in 2016 the National Assembly Research Service sided with the current ruling party's interpretation when it said an impeachment motion for an acting president requires the same number of votes as one for president.

The ruling and the main opposition parties have opposing views on appointing three new justices to the Constitutional Court. The nation's highest authority on the Constitution currently only has six justices on its bench -- the bare minimum to authorize an impeachment ruling.

The law requires the approval of at least six justices for the court to uphold an impeachment, and at least seven to deliberate an impeachment case. The court is deliberating the Yoon case, since the latter clause has been suspended, but reaching a decision on a presidential impeachment with just six justices is widely regarded as a risky move.

Rep. Kwon Seong-dong, the floor leader and acting leader of the People Power Party, said the acting president should not appoint a Constitutional Court justice when the sitting president has not yet been formally impeached.

The Democratic Party of Korea said the three candidates for the justice positions have already been nominated by the National Assembly, and Han's approval is merely a formality.

Han took over as the interim leader of Korea, with Yoon undergoing an impeachment trial and criminal investigation for insurrection and abuse of power regarding his imposition of martial law on Dec. 3-4.