South Korea's top court upheld a previous court decision on the confidante of ousted former President Park Geun-hye regarding a major influence-peddling and corruption scandal.

The Supreme Court on Thursday confirmed the Seoul High Court's ruling in February that sentenced Choi Seo-won to 18 years in prison on a string of corruption charges, including abuse of authority and bribery.

The top court also ordered a 20-billion-won fine and a six-point-three-billion-won forfeiture, upholding the lower court decision.

Choi Seo-won, formerly known as Choi Soon-sil, was convicted of exploiting her ties with Park to force 50 companies to cough up a combined 77-point-four billion won for two of her nonprofit foundations.

She was also accused of meddling in state affairs without holding an official position within the Park government.

Last August, the top court rejected the previous high court ruling, dismissing charges of coercion in demanding conglomerates make foundation donations.

The Supreme Court on Thursday also confirmed a lower court decision sentencing former senior presidential secretary An Chong-bum to four years in prison, a fine of 60 million won and a forfeiture of 19-point-nine million won.