An appeals court on Friday reduced the sentence for the son of a former aide to the parliamentary speaker indicted over threatening to bomb Cheong Wa Dae.

The Seoul High Court sentenced the 22-year-old, surnamed Kang, the son of a former aide to National Assembly Speaker Chung Ui-hwa, to six months in prison for calling the presidential office in January to say he was going to bomb the office.

He had received an eight-month jail term in a lower court for posting threatening tweets on Twitter, a popular social networking service.

The high court said some of the tweets he posted had failed to threaten President Park Geun-hye as there is no proof Park was aware of the threat, which is different from the lower court's ruling where intimidation charges were convicted.

Judge Kim Yong-bin also acquitted Kang of the charge on the obstruction of duties for causing police and soldiers to mobilize on false reports. 

"The reports were made by a third party, not Kang, which means the police and soldiers were just carrying out their tasks," Kim added. (Yonhap)