SEOUL—South Korea’s legislature voted to impeach acting President Han Duck-soo on Friday after he declined to make judicial appointments needed to advance the impeachment of his predecessor, extending the political upheaval that began with a short-lived martial law declaration earlier this month.

The vote intensifies a political crisis as the Constitutional Court meets for its first hearing on suspended President Yoon Suk Yeol's short-lived martial law.

Finance Minister Choi Sang-mok became on Friday South Korea's second acting president in two weeks, as lawmakers voted to impeach the current acting leader, Prime Minister Han Duck-soo, fuelling political uncertainty in Asia's fourth-largest economy.