North Korea on Thursday confirmed it had arrested an American citizen and was preparing to charge him with "crimes against the nation."

The man, identified as Jun Young-Su, was reportedly involved in religious activities when he was detained in November last year, AFP reported.

Jun was being investigated "for committing a crime against the DPRK [North Korea] after entering it," the country's state news agency said.

The U.S. State Department disclosed the detention on Tuesday, saying that Swedish diplomats had been given access. It appealed for the man's release on humanitarian grounds.

Bloomberg cited South Korean news reports said the man was from Orange County, California, and had recently done business in North Korea, which normally limits access to Americans.

AFP quoted a source in Seoul familiar describing the man as a Korean-American businessman in his 60s, saying he was detained for involvement in missionary work.

North Korea has a deep hostility towards organized religious groups, viewing them as a challenge to Pyongyang's Stalinist leadership.

North Korea has detained several U.S. citizens in recent years, adding to tensions already heightened by Pyongyang's nuclear ambitions.

In 2010, former U.S. President Jimmy Carter mediated to secure the release of Aijalon Mahli Gomes, an American sentenced to eight years hard labor for crossing the border from China.

Lisa Ling and Euna Lee, two American journalists sentenced to 12 years hard labor for entering North Korea in 2009 were released following intervention from former U.S. president Bill Clinton.