A former chief of the state spy agency on Monday appealed against a suspended jail sentence for intervening in the 2012 presidential election through an online smear campaign in favor of President Park Geun-hye, then ruling party candidate.

In a high-profile ruling, the Seoul Central District Court sentenced Won Sei-hoon, former director of the National Intelligence Service (NIS), to two years and six months in prison, suspended for four years, for election meddling.

The 63-year-old was found guilty of leading an online smear campaign against Park's rival candidate from the main opposition camp ahead of the presidential poll, in violation of the law prohibiting NIS officials from intervening in domestic politics.

His lawyer filed the appeal with the Seoul Central District Court, saying that the online campaign was part of the spy agency's routine anti-North Korea psychological warfare.

"The NIS has been doing psychological warfare activities for a long time, including when the country was ruled by liberal governments," Won's lawyer said. 

"The activities lasted up until now although their content may vary depending on the nature of each administration. But it's not right to criminalize such activities done under Won's leadership," he added.

Won, a close aide to former President Lee Myung-bak, headed the NIS for about four years until early 2013. (Yonhap)