Pyonyang, Feb 27 (IANS): A South Korean missionary arrested for allegedly trying to establish underground Christian churches across North Korea apologised here Thursday "for his anti-state crimes".

Kim Jung Wook, 50, who was arrested in early October, right after "illegally sneaking into Pyongyang with Christian instructional materials and porn movies", told a press conference he was attempting to overthrow the North Korean regime and had received assistance from South Korea's intelligence agency.

Kim said he had met many times with South Korean intelligence officials before crossing into North Korea from the Chinese border town of Dandong, and claimed he had received thousands of dollars from them for his service.

"I told the North Korean people I met that we should build God's nation and break down the North political system," Xinhua quoted Kim as saying in the press conference.

Kim told Xinhua he was not sure what consequences he would face, and asked for mercy from the DPRK authorities.

Kim also told reporters he wished "his appearance at this time would not affect relations between north and south", adding he requested the press conference to let his family know he was "doing well".

The press conference came only a few days after the two Koreas showed signs of warming ties with the reunions of separated families split by the 1950-53 Korean War for the first time in three years.

Seoul Thursday responded to Kim's appearance by asking Pyongyang to send him back as soon as possible.

Pyongyang said in November last year it had arrested a South Korean spy and was investigating him on charges of espionage.

But South Korea's National Intelligence Service said it had "nothing to do with Kim".