South Koreans begin early voting to replace ousted Park Geun-hye

South Koreans began early voting on Thursday in the election to replace ousted President Park Geun-hye.

Early voters can cast ballots on Thursday and Friday at about 3,510 polling stations across the country before the election next Tuesday, the National Election Commission said in a statement.

It's South Korea's first presidential election with early voting after introducing it for parliamentary and mayoral elections in recent years, the statement said.

Pre-election surveys show liberal candidate Moon Jae-in comfortably leading his two main rivals - a centrist and a conservative. The winner will be sworn in as the new president immediately, forgoing the usual two-month transition.

Park's impeachment and removal from office changed South Korea's election schedule, so the new president will serve one full five-year term.

Park is currently jailed at a detention centre near Seoul awaiting her trial on allegations that she extorted money from businesses, took kickbacks from some of those companies and committed other wrongdoing, all in collaboration with a longtime confidante. The trial is to formally start later this month.

A commission-run website showed about 4 million people had voted by midafternoon. South Korea has 42,479,710 eligible voters, according to the election commission.