Seoul, May 4 (IANS): The Seoul government on Monday urged North Korea to release a South Korean college student with a US green card detained in Pyongyang for illegal entry.

North Korea announced over the weekend that it has detained Joo Won-moon, 21, who was studying at the New York University, Yonhap News Agency reported.

Pyongyang said it arrested him on April 22 for illegally entering the country through Dandong in China's Liaoning province.

South Korea urged North Korea to release Joo as soon as possible and also called for guarantee of his personal safety.

South Korea's Unification Ministry also called for the release of three other South Koreans who have been detained in North Korea.

Kim Jung-wook, a South Korean missionary, was sentenced last year by a North Korean court to hard labour for life after being convicted of espionage and setting up underground churches. He was arrested in October 2013.

Kim Kuk-gi and Choe Chun-gil were arrested on charges of spying activities for South Korea's National Intelligence Service.