North Korea has confirmed that it has arrested a US citizen and is preparing to charge him with "committing a crime" against the country.
Jun Young-su was arrested in November last year, the official KCNA news agency said.
The US state department announced the arrest on Tuesday and is calling for the detainee's release on humanitarian grounds.
The US has not named him, but said that Swedish diplomats had visited him.
The Swedish embassy in Pyongyang looks after American interests, as there are no diplomatic relations between North Korea and the US.
North Korea did not specify the crimes of which the man had been accused.
But South Korean media reports suggested he was a Korean-American businessman who could have been involved in Christian missionary work.
North Korea sees organised religious activity as a potential challenge to the leadership.
It has detained a number of US citizens in recent years.
In 2010 devout Christian Aijalon Gomes was sentenced to eight years' hard labour for entering North Korea. He was freed after seven months when former US President Jimmy Carter flew to Pyongyang for talks.
Two US journalists, Laura Ling and Euna Lee, were held for several months after their arrest in 2009 for trespassing across the China-North Korea border. Former President Bill Clinton flew to Pyongyang to secure their release.
The news of Mr Jun's arrest comes ahead of another visit to Pyongyang by Mr Carter.
He says he wants to discuss how to revive stalled talks aimed at ending North Korea's nuclear programme.
North Korea has conducted two nuclear tests to date and tensions have been high on the Korean peninsula since the sinking of the Cheonan, a South Korean warship.
The ship went down with the loss of 46 lives near the disputed inter-Korean border in March 2010. Seoul says Pyongyang sank the vessel- North Korea denies any role.
A North Korean artillery attack on a border island in November that killed four South Koreans led relations to further deteriorate.
Were North Korea to allow Mr Jun to return home with Mr Carter, critics would see it as part of a planned attempt by the communist government to appear reasonable and so deserving of political concessions and economic aid, says the BBC's Nick Ravenscroft in Seoul.