SEOUL (REUTERS) - South Korea's Supreme Court on Thursday (July 16) overturned an abuse-of-power conviction against a prominent liberal politician, keeping alive his chances of being a top contender in the next presidential election, in 2022.

Mr Lee Jae-myung, the governor of Gyeonggi province, was convicted in 2019 of abuse of power and lying about his attempt to incarcerate his brother in a mental hospital in 2012.

He was fined three million won (S$3,470), which according to the law, strips him of eligibility to run for public office.

But Chief Justice Kim Myeong-su ruled that Mr Lee's remarks about his brother, made in a 2018 election debate, were in response to questions from an opponent and it was undemocratic for a state institution to regulate such comments.

"Such remarks cannot be regarded as a public act as their intention was to actively and unilaterally disclose factual information regardless of the debate topic or context," Mr Kim said.

Mr Lee thanked the top court in a Facebook post for what he called a just decision.

"You have reaffirmed the faith that fake cannot defeat the truth," he said.

"I have just realised how lucky I am to even be able to breathe here... As grateful I am for the opportunity to continue my work."

A former human rights lawyer and activist, Mr Lee, is considered a likely top contender for the 2022 presidential election, consistently ranking second in opinion polls among possible liberal candidates.

President Moon Jae-in was elected in 2017.

Presidents in South Korea serve one five-year term.