South Korea's top court has confirmed a lower court ruling that sentenced former presidential chief of staff Kim Ki-choon to one year in prison for illegally supporting conservative groups during the previous Park Geun-hye administration.

The Supreme Court said on Thursday that the appellate court's one-year jail term for Kim on charges of abuse of authority to obstruct the exercise of rights was upheld.

Kim was indicted for pressuring the Federation of Korean Industries(FKI) to provide six-point-nine billion won between 2014 and 2016 to 33 conservative activist groups supportive of the Park administration.

In the previous ruling, the Seoul High Court handed down an 18-month sentence after convicting Kim of abuse of power, as well as extortion, but the Supreme Court ordered a review earlier this year while rejecting the extortion conviction.

Seoul High Court reduced the prison term to one year in the subsequent retrial.

Kim had already spent a combined 987 days behind bars for the so-called "white list" case, as well as a separate conviction for drafting a blacklist of artists critical of the conservative Park government.