South Korea's former Prime Minister Han Duck-soo says he will run in next month's presidential election and would seek to lessen the powers of the office and ease strife-ridden domestic politics if he wins.

South Korea's top court cast doubt on Thursday on frontrunner Lee Jae-myung's eligibility to run for the presidency, while the resignations of the prime minister and finance minister shook the interim government in place since December's martial law.

The appointment of a new acting president came as Han’s candidacy injected more uncertainty into an election race that has been upended by doubts over the eligibility of the lef