A South Korean Baptist missionary who was arrested more than four months ago for allegedly trying to establish underground Christian churches in North Korea told reporters Thursday he is sorry for his "anti-state'' crimes and appealed to North Korean authorities to show him mercy by releasing him from their custody.

Kim Jung Wook told a news conference he was arrested in early October after entering the North from China and trying to make his way to Pyongyang with Bibles, Christian instructional materials and movies. He said he had received assistance from South Korea's intelligence agency.

Kim said he was unsure what punishment he would face. He asked for the mercy of North Korean authorities and said he requested the news conference to show his family he is in good health. He said he was arrested on Oct. 8, the day after he crossed into the North.

Kim, in his first public appearance since his arrest, said he had met numerous times with South Korean intelligence officials before crossing into the North from Dandong, in China, and claimed he had received thousands of dollars from them for his service. He said he wanted to go into North Korea to establish a series of underground churches to spread Christianity there.

"I was thinking of turning North Korea into a religious country, and destroying its present government and political system,'' he said. "I received money from the intelligence services and followed instructions from them, and arranged North Koreans to act as their spies. And I also set up an underground church in China, in Dandong, and got the members to talk and write, for me to collect details about the reality of life in North Korea, and I provided this to the intelligence services.''

North Korea's state media said in November the country had arrested a South Korean spy. South Korea's main spy agency, the National Intelligence Service, denied it had sent such a spy to North Korea.

At Thursday's news conference, Kim said his actions constitute a crime against North Korea's state and called himself a "criminal.'' He said that he has not been mistreated during his incarceration. Similar statements in the past have been recanted after prisoners have been released, however.

It was not clear what kind of punishment Kim would receive, or why North Korean officials held the news conference, during which they also showed video-taped confessions of North Koreans Kim had contact with.

While North Korea's constitution guarantees freedom of religion, in practice only sanctioned services are tolerated by the government.

A similar news conference was held in January by another jailed missionary, Korean-American missionary Kenneth Bae, who was detained while leading a group on a tour of North Korea in 2012 and later sentenced to 15 years of hard labor for what Pyongyang says was an attempt to topple its regime. Bae was moved to a hospital last summer in poor health, but said at the news conference that he was being transferred back to prison.

Earlier this week, John Short, a missionary from Australia, was arrested in Pyongyang for allegedly trying to distribute Christian materials while in the country with a tour group. Australia does not have a diplomatic office in Pyongyang and is being represented by the Swedish Embassy, making it difficult to obtain even basic details on his case.

The North Korean government has not made any statements on Short, 75, who has lived in Hong Kong for 50 years and has been arrested previously in China for evangelizing. (AP)