The man accused of stabbing South Korean Opposition leader Lee Jae-myung in the neck told investigators that he wanted to kill him to prevent him from becoming the country's president, police said Wednesday.

Lee was released Wednesday from the hospital after eight days of treatment, including surgery.

Police said they believe the suspect acted alone when he attacked Lee, 59, in the southeastern city of Busan on January 2, leaving him bleeding and slumping on the ground.

During questioning, the suspect said he had determined to kill Lee to prevent him from running for South Korea's presidency, Busan police chief Woo Cheol-Mun told a televised briefing. Woo said the suspect said he was unsatisfied with what he believes were authorities' failures to punish Lee over his corruption allegations.

Woo said the suspect left a eight-page note that shows similar motives for his attack. Woo said the suspect bought an outdoor knife last April and followed Lee on five events since June.

“It's analyzed that the suspect's subjective political belief led to the extreme crime,” Woo said.

During police questioning, the suspect had no defense lawyer, according to Busan police.

Police handed over the suspect to prosecutors, who will determine whether to indict him and send him to a trial. If he's indicted but still has no lawyer, a court will appoint one. A Busan court earlier approved an arrest warrant for him on alleged attempted murder.

“I caused concerns. I'm sorry,” the suspect, who was not identified, said in brief comments to reporters at the Busan police station. Asked by a reporter whether he plotted the attack alone, he said, “Yes. How could I plan this with someone else?”

Democratic Party officials confirmed the suspect became a member last year. The ruling People Power Party said he is currently not their member but media reports said the man was previously affiliated with the party's predecessor.

Earlier Wednesday, Lee expressed hopes for an end of “politics of hatred” when he left Seoul National University Hospital.

“Our respected and dear citizens, I feel sorry for causing concerns for you and I'd like to say thank you. Our people saved me,” Lee said, as his supporters shouted his name.

Lee said he hopes the attack will serve as a chance “to end politics of hatred and politics of confrontation and return to politics of mutual respect and co-existence.”

Lee, from the Democratic Party, is a tough-speaking liberal who narrowly lost the 2022 presidential election to President Yoon Suk Yeol. Their closely fought race and post-election political bickering have intensified South Korea's already-toxic conservative-liberal divide.

Lee is a vocal critic of Yoon's major polices. He faces an array of corruption allegations and related trials and investigations. Lee has denied any legal wrongdoing and accuses Yoon's government of pursuing a political revenge.

According to recent surveys, Lee is one of the early favourites for the 2027 presidential election. Yoon is by law barred from seeking reelection.