The North Korean government says it detained a US national for illegally entering the country last week. Pyongyang did not release his identity.

However, colleagues say the man is a Christian activist who crossed into North Korea from China on Christmas Day using the frozen Tumen River that forms the border between the two countries.
 

The man, who has been identified as 28-year-old Robert Park, a US citizen of Korean descent, apparently crossed the border as part of a one-man protest. He had a written message for North Korean leader Kim Jong-Il, whic called on the hardline Communist to free political prisoners and improve the human rights situation in the country.
 

Earlier this year, two US journalists were arrested in North Korea. They were released four months later.