South Korea has confirmed that North Korea detained a South Korean student of New York University, but says it's still unclear whether the 21-year-old New Jersey resident attempted to enter the North illegally.

An official from Seoul's Unification Ministry said Sunday his department is still trying to gather information on Won Moon Joo's travels and the circumstances of his arrest.

North Korea's official Korean Central News Agency said Saturday that Joo was arrested on April 22 after trying to illegally enter North Korea from the Chinese border town of Dandong.

North Korea has occasionally detained South Koreans, Americans and other foreigners, often on accusations of spying, in what analysts say are attempts to wrest outside concessions.