North Korea has detained an American who demanded asylum after arriving in the country on a tourist visa in "a gross violation of its legal order."
The 24-year-old had tried to enter the country on a tourist visa but tore it up and shouted he wanted asylum, according to state media.
The announcement was made while US President Barack Obama was visiting South Korea, one of Washington's closest allies and still technically at war with Pyongyang.
"A relevant organ of the DPRK put in custody American Miller Matthew Todd, 24, on April 10 for his rash behaviour in the course of going through formalities for entry into the DPRK to tour it," North Korea's KCNA news agency said, using the country's official name, the Democratic People's Republic of Korea.
KCNA said the detained man had a tourist visa for the DPRK, but tore it to pieces and shouted that he had come "to the DPRK after choosing it as a shelter."
The US State Department said it was aware of reports that a U.S. citizen had been detained in North Korea and it was in touch with the Swedish Embassy in Pyongyang on the issue.
The United States has no diplomatic relations with North Korea and the interests of its citizens in the country are represented by Sweden.
While KCNA identified the man as Miller Matthew Todd, it appeared that it had used the Korean convention of putting the last name first, followed by the first and middle names. As a result, the man's name was likely to be Matthew Todd Miller.
Kenneth Bae, a Korean American missionary, has been held in North Korea for more than a year. He was arrested as he led a tour group in the country in 2012 and sentenced to 15 years of hard labor on charges of state subversion.
North Korea has twice cancelled visits by Robert King, the US special envoy for North Korean human rights issues, to discuss Bae's case.