SEOUL (Kyodo) -- The chief of South Korea's ruling People Power Party said Thursday it will do its utmost to prevent the passage of an impeachment motion against President Yoon Suk Yeol following his short-lived declaration of martial law.

But Han Dong Hoon demanded that Yoon quit the party and said the president and others responsible for the martial law declaration, which lasted only six hours from late Tuesday before being rescinded, must be held accountable for causing public anxiety.

After martial law was declared, soldiers were sent to the parliament building but they were withdrawn after lawmakers passed a resolution to lift the declaration.

The main opposition Democratic Party, which holds a majority in the National Assembly after the PPP suffered a defeat in April legislative elections, and five other parties filed an impeachment motion Wednesday.

While Han said the PPP will seek to block the passage of the motion to avoid political chaos, he emphasized its opposition is not aimed at defending the president's "unconstitutional" martial law declaration.

The DP said it plans to hold an impeachment vote at parliament at around 7 p.m. Saturday. Impeachment requires support from two-thirds of the 300 members of the unicameral legislature, which means at least eight votes from the ruling party are needed.

If the bill is passed, Yoon's presidential authority would be suspended. His formal impeachment would then need to be approved by the Constitutional Court.

Yoon's administration has been thrown into turmoil, with all of his Cabinet members offering to resign, according to local media reports Wednesday.

Earlier Thursday, Yoon approved Defense Minister Kim Yong Hyun's resignation to take full responsibility for the situation stemming from the declaration of martial law. Kim reportedly suggested the declaration to the president.

Prosecutors imposed a travel ban on Kim after a group of minor political parties filed a complaint that Kim, Yoon, and Army Chief of Staff Gen. Park An Su committed treason through their roles in the declaration of martial law, Yonhap News Agency reported.

Both prosecutors and the police are expected to begin an investigation into the procedure taken by Yoon, who allegedly failed to meet the constitutional requirements for declaring martial law.