The top court on Thursday found a former head of the state-run Korea Development Bank guilty of slandering Lotte Group Chairman Shin Dong-bin.

The Supreme Court upheld the lower court's defamation conviction of Min Euoo-sung and a 5 million won ($4,412) fine.

Min was sued by Shin and Lotte for telling reporters in October 2015 that Shin Kyuk-ho, the chairman's father and the group founder, was "caged up" in his office at Lotte Hotel in central Seoul and that he was being "surveilled" by his son. 

His remarks came amid an ongoing family squabble at the retail conglomerate between the chairman and his elder brother over leadership succession. Min is known to be in support of the founder Shin and his eldest son, Dong-joo.

The lowest court found him guilty of slandering and obstruction of business. But the appeals court cleared him of the obstruction of business charge, saying that it's unlikely Lotte's business was affected by his remarks. The top court agreed to the latter ruling. (Yonhap)