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.

South Korea's Acting President Choi Sang-mok said on Friday the government will do its utmost to focus on stabilising state affairs amid ongoing political turbulence stemming from the short-lived imposition of martial law earlier this month.

Choi, 61, a veteran economic technocrat who has served for more than 30 years at the finance ministry, takes on an unprecedented role as successor to an impeached acting leader.