Former President Yoon Suk Yeol has defiantly refused questioning over a bungled martial law decree last month.

The impeachment of South Korea’s acting President Han Duck-soo has plunged the country into further political turmoil, coming less than two weeks after lawmakers impeached President Yoon Suk Yeol.

Protesters have thronged the official residence of impeached President Yoon Suk Yeol, where officials trying to arrest him were blocked by security guards.

The impeachment of Han Duck-soo, acting president since Yoon was impeached on Dec. 14 for declaring martial law, has thrown South Korea's once-vibrant democratic success story into uncharted territory.

Acting President Han Duck Soo blocked the appointment of three judges that Parliament had selected to oversee his predecessor's impeachment.

South Korea's opposition Democratic Party submitted an impeachment motion against embattled acting President Han Duck-soo on Thursday in the latest challenge to the country's leadership structure.

South Korea's opposition-controlled National Assembly voted Friday to impeach acting President Han Duck-soo despite vehement protests by governing party lawmakers, further deepening the country's political crisis set off by President Yoon Suk Yeol's stunning imposition of martial law and ensuing impeachment.

Yoon Suk-yeol retains the title but not the power of president while the constitutional court decides whether to approve the motion to impeach him.

South Korea's acting President Choi Sang-mok said on Tuesday he would immediately move to fill vacancies on the Constitutional Court in a effort to restore stability after the impeachment of two of his predecessors this month triggered political turmoil.