South Korea's conservatives made another about-face on Saturday and reinstated their nominee, just hours after dropping him and reopening the nomination process as the divided party struggled for unity to challenge the liberal frontrunner in a presidential election four weeks away.

SEOUL (Reuters) - South Korea's conservatives dropped their presidential candidate on Saturday and reopened a process to pick a new nominee as the country's former prime minister joined the party to challenge a liberal frontrunner less than four weeks before the election.

South Korea's People Power Party registered former labour minister Kim Moon-soo as its official presidential candidate on Sunday, a day after it attempted to cancel his candidacy.