Han has been the caretaker leader after President Yoon Suk Yeol was impeached by the assembly over his short-lived imposition of martial law earlier this month.

South Korea's main opposition party introduced a bill to impeach acting President Han Duck-soo on Thursday, a day before it plans to seek a vote on the move, which could deepen a constitutional crisis triggered by a short-lived martial law.

South Korea's opposition said Thursday it filed an impeachment motion against acting president Han Duck-soo, in an escalating row over the composition of the Constitutional Court which would decide whether to remove his predecessor from office.