SEOUL, Feb. 9 -- South Korea's ex-spy agency chief on Monday was sentenced to three years in prison on charges of intervening in the 2012 presidential election.

The Seoul High Court overturned a previous low court ruling, which gave Won Sei-hoon, head of the National Intelligence Service (NIS), a prison term of two and a half years.

After the overturning, the 62-year-old was taken into custody at the court.

The court said Won violated the NIS act as well as the election law, which ban public officials from engaging in election campaign activities.

The court ruling said Won instructed his subordinates to intervene in domestic politics, in violation of the election law by meddling in the 2012 presidential election.

It said NIS officials were ordered by Won to use more than 700 Twitter accounts to post around 274,800 negative comments online against opposition candidates and in favor of the then ruling party hopeful Park Geun-hye during the 2012 election.