The country’s opposition has accused acting president Han Duck-soo of obstructing justice and aiding the failed martial law bid.

Prime Minister Han Duck-soo, who became South Korea's acting president after Yoon Suk Yeol's impeachment, is a career technocrat whose wide-ranging experience and reputation for rationality may not be enough to stem the country's deepening political crisis.

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