Poll says he is now in second place, behind potential rival Moon Jae-in

Former UN secretary-general Ban Ki-moon said on Thursday he will announce soon whether he will run for South Korea's presidency, as he returned home and strongly hinted at his political ambitions before hundreds of cheering supporters.

Ban's return will likely heat up local politics as he's considered the only major conservative contender in a possible early election to replace impeached President Park Geun-hye. Dozens of lawmakers have already bolted from Park's conservative ruling party and want to align with Ban, while the main liberal opposition party is escalating its political offensive against him.