SEOUL (AFP) - A South Korean court on Tuesday sentenced the head of a traditional dance troupe to four years in prison after he was convicted of passing information to a North Korean spy.

The Seoul Central District Court ruled that Jeon Shik Ryeol, 44, had violated the national security law which bans South Korean citizens from making unauthorised contact with North Koreans.

Jeon, the head of the traditional Korean dance company "Chool", is a member of the left-wing Unified Progressive Party.

Prosecutors said the dancer met a North Korean spy in Shanghai in March 2011, and sent an encoded oath of loyalty to Pyongyang a month later.

He was also convicted of passing on details of a factional feud within his party in 2012.

In February, Lee Seok-Ki, a legislator from the same left-wing party as Jeon, was sentenced to 12 years in prison after a rare treason trial saw him convicted of plotting an armed revolt in support of North Korea.