(CNN) -- North Korea on Thursday showed off a South Korean man it has detained on spying charges.
The man, named as Kim Jung-wook, was presented to foreign journalists in Pyongyang, the Japanese news agency Kyodo reported.
Speaking in front of reporters, Kim apologized for having carried out "anti-state" activities at the direction of South Korea's National Intelligence Service, according to Kyodo, which has a bureau in Pyongyang.
He said he had worked as a missionary for several years on the Chinese side of the border with North Korea, running a church that sought North Korean converts.
North Korea said in November that it had it had arrested an unidentified South Korean intelligence agent in Pyongyang who was planning to "rally dishonest elements" in North Korea and "use them for undermining the stability of the social system."
Pyongyang said the agent had engaged in "espionage and plot-breeding activities in a third country" that borders North Korea while "disguising himself as a religionist."
It wasn't immediately clear how much of what Kim told reporters Thursday was grounded in truth. North Korea is known to push detainees to make false confessions.
Merrill Newman, an American veteran of the Korean War detained by North Korea last year, said that he was made to deliver an "apology" on state media that was not his own words.
The South Korean Unification Ministry said Thursday it had been asking North Korea for information about the South Korean citizen since Pyongyang's announcement in November.
But it said it hadn't received any information until Kim's appearance Thursday.
"We strongly request the release of the South Korean citizen as soon as possible," said Unification Ministry spokesman Kim Eui-do.
The South's National Intelligence Service said it had nothing to do with Kim Jung-wook's case.
A slight thaw
Kim's appearance in Pyongyang comes amid a slight thaw in North-South relations. The two countries just held reunions of families separated by the Korean War for the first time since 2010.
North Korea is currently known to be holding two foreign missionaries: Korean-American Kenneth Bae, 45, who has been in detention since November 2012; and the 75-year-old Australian John Short who was detained earlier this month.
North Korea has a number of state-controlled churches, but the authoritarian Communist regime doesn't tolerate independent religious activities.
The regime "considers the spread of Christianity a particularly serious threat, since it challenges ideologically the official personality cult and provides a platform for social and political organization and interaction outside the realm of the state," a United Nations panel said in a report released this week.
"People caught practicing Christianity are subject to severe punishments in violation of the right to freedom of religion and the prohibition of religious discrimination," the report by the United Nations Commission of Inquiry on Human Rights in North Korea said.
CNN's Judy Kwon, Tim Schwarz and Yoko Wakatsuki contributed to this report.