By Jeremy Laurence
SEOUL (Reuters) - U.S. rights envoy Robert King on Friday won the release of an American citizen detained in North Korea on unspecified charges for the past six months, as he wrapped up a visit to the secretive state to assess its pleas for food aid.
The U.S. State Department said it had been informed by Sweden, which looks after U.S. interests in North Korea in the absence of formal diplomatic ties, that Jun Young Su would be freed.
"We welcome North Korea's decision to release him on humanitarian grounds," State Department spokesman Mark Toner told a briefing in Washington.
The North's KCNA state news agency said King had expressed regret about the case, and as a result Pyongyang had agreed to release Jun.
King was due to depart the North's capital on Saturday after a five-day visit. Toner said Jun would leave North Korea separately.
Jun was arrested last November, and admitted committing a crime "against the state" during an investigation, KCNA reported.
Media reports say Jun was a businessman from California and that he had been doing missionary work in the isolated North.
There is a long history of the North detaining U.S. citizens and releasing them with great reluctance.
The main purpose of King's mission, the first ever by a rights envoy to the North, is to evaluate the destitute state's pleas for food aid and whether the United States should help.
Toner said the food issue, along with broader questions about the future of multilateral talks on North Korea's nuclear program, was unrelated to the Jun case.
"There are a number of things we would like to see North Korea do, in improving relations with South Korea first and foremost, before we see other steps on other issues," he said.
"We're happy that an American citizen who was being held there has been released but we're still going to look for concrete actions on other areas."
U.S. UNDER PRESSURE
The North, squeezed by tightened international sanctions for nuclear and missile tests in 2009, has asked about 40 countries for food aid, although South Korea and some high-profile U.S. senators have questioned its claims of food shortages.
Pyongyang, hit by chronic shortages for decades, says supplies have been worsened by poor harvests and bad weather.
The United States is under pressure to resume food aid after the United Nations said in a report this year that more than 6 million North Koreans urgently needed help.
Washington has stressed that King's trip did not mean a resumption of aid was imminent. Some members of the U.S. assessment team will stay on in North Korea until next week.
The United States suspended food supplies to the North in 2008 over a monitoring dispute and has said it will only resume them with the South's agreement.
King's visit, the first official U.S. trip to North Korea since 2009, comes as the United States may be looking to revive multilateral talks on the North's nuclear program after a hiatus of more than two years.
The North's leader, Kim Jong-il, met Chinese President Hu Jintao in Beijing this week, and while there was no breakthrough on stalled six-party nuclear talks, Kim indicated he was not spoiling for fresh fights.
Last year tension spiked on the peninsula after two attacks killed 50 South Koreans.
The 69-year-old North Korean leader returned home early on Friday, ending his third visit to the North's powerful ally in a year.
(Additional reporting Jack Kim and Andrew Quinn in Washington; Editing by Robert Birsel and Xavier Briand)