Lawmakers take part in the plenary session at the National Assembly in Seoul, Dec. 11. Yonhap

The National Assembly is set to open a plenary session Thursday to vote on a special counsel bill to investigate whether President Yoon Suk Yeol committed insurrection and other violations over his short-lived declaration of martial law last week.

The Assembly will also vote on a bill mandating a special counsel probe into two key allegations involving first lady Kim Keon Hee — her alleged involvement in a stock manipulation scheme and interference in election nominations through a power broker.

This is the fourth version of the bill targeting the first lady following a similar proposal vetoed by Yoon last month, which was ultimately scrapped in a revote last Saturday.

The bill was just two votes short of the 200 votes needed from the 300-member National Assembly to override the veto.

Additionally, the main opposition Democratic Party of Korea (DPK) will introduce a new impeachment motion against Yoon later in the day and report it to the plenary session. It aims to put the motion up for a vote during an upcoming parliamentary plenary session Saturday.

By law, an impeachment motion must be put to a vote between 24 and 72 hours after it is reported to a plenary session.

The DPK also plans to put to a vote impeachment motions against Justice Minister Park Sung-jae and Cho Ji-ho, head of the Korean National Police Agency, on Thursday.

On top of the special counsel probe bill against Yoon, the National Assembly has passed an opposition-led bill calling for a "permanent" special counsel to investigate his martial law imposition.

Unlike a regular special counsel probe, the president cannot exercise the right to veto a bill over a permanent special counsel, though he can delay the appointment of the counsel itself. (Yonhap)