North Korea confirmed Friday that it had arrested a US citizen in November, saying legal action would be taken against him but giving no details of the charges.
The man, identified as Pae Jun-Ho, entered North Korea on November 3 as a tourist, and "committed a crime" against the country, the official Korean Central News Agency (KCNA) said.
"He was put into custody by a relevant institution," it added.
The United States has no diplomatic ties with North Korea and KCNA said consular officials from the Swedish embassy, which acts on behalf of the US, had visited Pae on Friday.
"Legal actions are being taken against Pae in line with the criminal procedure law" of North Korea, the agency said without elaborating.
The arrest was first reported earlier this month by a South Korean newspaper which had identified the detainee as a a 44-year-old Korean-American tour operator.
KCNA said Pae was detained as he entered the north-eastern port city of Rason which lies inside a special economic zone near North Korea's border with Russia and China.
Several Americans have been held in North Korea in recent years.
In 2010 former US president Jimmy Carter won plaudits when he negotiated the release of American national, Aijalon Mahli Gomes, sentenced to eight years of hard labour for illegally crossing into the North from China.
On another mercy mission a year earlier in 2009, former president Bill Clinton won the release of US television journalists Laura Ling and Euna Lee, jailed after wandering across the North Korean border with China.