South Korean opposition leader Lee Jae-myung, who is the front-runner in opinion polls to be the country's next leader, declared his bid for the presidency on Thursday, promising to fix inequality and spur economic growth.

The presidential election will be held on June 3, after the impeachment of former president Yoon Suk Yeol for his December martial law declaration was upheld on April 4.

In a video released on Thursday, Lee pledged to fix economic polarization that he said was a key source of social conflict, highlighting how he felt this had exacerbated the recent political turmoil in the wake of Yoon's martial law order.