Access to foreign pop culture is strictly banned for ordinary people in North Korea, with violators facing hefty fines or jail terms.
However, a growing stream of pirated DVDs and music CDs smuggled from China has made South Korea's pop culture increasingly popular.
The prison official said, “it was the first time the number of people jailed solely for watching the South's TV dramas has gone over 1,000. Now, the prison is overcrowded with such prisoners,"
The group also claimed that Pyongyang had created a special police unit in January to crack down on those with "rotten spirit".
"Those who are caught are usually jailed for between two and five years and face harsher treatment in prison than other offenders," the police unit official said.