SEOUL, South Korea (AP) — South Korea is backing a push by a rights activist to raise his claim with the United Nations that he was tortured during his four-month detainment in China.

A spokesman for activist Kim Young-hwan said Wednesday that Chinese authorities burned the South Korean with an electronic rod, kept him from sleeping and hit his face. Spokesman Choi Hong-jae said Kim will raise his case with a U.N. human rights organization.

South Korea's Foreign Ministry says China must thoroughly investigate and punish those involved. China's Foreign Ministry denies any torture but says authorities are investigating.

Kim returned to South Korea last month with three other activists. He was detained for allegedly undermining China's state security. Kim told reporters last week that he visited China to support North Korean defectors there.