South Korea's Supreme Court on Thursday confirmed a seven-year prison sentence for the CEO of the company that operated the ill-fated Sewol ferry, which sank last year with the loss of more than 300 lives.

The ruling upheld the sentence passed by an appeals court in May, which found Kim Han-Sik, the president of Chonghaejin Marine Co., guilty of manslaughter and embezzlement.

Four other Chonghaejin officials were sentenced to jail terms ranging from two-and-a-half to four years.

The apex court agreed with the lower court finding that Kim had allowed the passenger ferry to be routinely overloaded and approved illegal renovations to increase its passenger capacity.

The Sewol sank in April, 2014, with the loss of 304 lives -- most of them high school students on an organised trip.

READ: Sewol Ferry: S. Korean divers struggle to open blocked cabins

Kim had challenged the manslaughter conviction, insisting he was just a salaried employee under the thumb of company owner Yoo Byung-Eun, who he described as deeply involved in the firm's operations.

Following the Sewol disaster, Yoo became the target of a massive manhunt. His badly decomposed body was found weeks later in a field.

PIC GALLERY: 1) Sewol sinking
                           2) Sewol: Remembering victims

                           3) Sewol: Final farewell