Prime Minister Han Duck-soo has been mulling whether to run for election, while the main opposition candidate and front-runner suffered a setback in court.

South Korea's former prime minister and acting president Han Duck-soo ended a short, ill-fated attempt to win the conservative party's presidential nomination on Sunday after days of internecine disputes just days out from the election.

South Korea’s acting leader, Prime Minister Han Duck-soo, says he is resigning amid reports he will run in next month’s presidential election.