The Supreme Court on Thursday overturned a ruling that convicted a senior opposition lawmaker of receiving 30 million won ($24,400) in kickbacks from a former banker, citing lack of credibility in testimonies.

Rep. Park Jie-won, formerly affiliated with the main opposition Minjoo Party, was indicted in September 2012 on charges of pocketing 80 million won from former bankers and a businessman in return for peddling influences over a prosecutors' investigation.

The Seoul High Court, partly accepting the charges, had sentenced Park to a year in prison, suspended for two years. The court also ordered the 73-year-old lawmaker to forfeit the 30 million won.

The Supreme Court, however, said a district court's initial ruling, which posed doubts on statements made by Oh Moon-chol, former head of a local savings bank suspected of bribing Park, was reasonable.

The top court said Oh's statements conflicted with that of other bribers and with the circumstantial factors.

The Seoul Central District Court had ruled in favor of the non-partisan lawmaker, acquitting him of all charges.

"After three years and a half of restraints, I was freed by the Supreme Court's retrial order," Park wrote on his Twitter after the ruling was delivered. "I thank the justice department for the wise decision and (South Korean) people, as well as the citizens of Mokpo for their support."

Mokpo, South Jeolla Province, located some 410 kilometers south of Seoul, is Park's constituency.

He left the Minjoo Party in January, saying he would integrate the divided opposition bloc. (Yonhap)