North Korea rejected Seoul's call for the release of a South Korean Christian missionary who has been held in the communist country for more than four months, officials said Friday.

South Korea had demanded that North Korea quickly release Kim Jong-uk and guarantee his safety before his repatriation to the South, according to the officials at the unification ministry, which handles inter-Korean relations.

It was not immediately clear if the North gave a reason for its refusal of the request delivered via the border village of Panmunjom separating the two Koreas.

Seoul's move came a day after Kim held his first news conference in Pyongyang since his arrest on Oct. 8, just a day after he illegally crossed into the North from China.

In November, Pyongyang said it had taken custody of an alleged South Korean spy, without disclosing his identity.

Kim said he was trying to set up a "head office of the dissident underground church network" in Pyongyang to help eventually topple the North, according to the Korean Central News Agency, the official propaganda organ of the North Korean government.

He also confessed to anti-state crimes during his news conference, according to the KCNA. (Yonhap)