(CNN) -- An American was detained in North Korea for trespassing on the country's border with China, state-run KCNA reported Thursday.
The unidentified individual was detained on Monday, and the incident is under investigation, according to KCNA's report.
The United States is aware of the report but had no additional details, a State Department official said.
It's thought that Pyongyang also is holding a Korean-American missionary who has been missing since late December.
North Korea announced on December 29 that it was holding an American who had entered the country illegally from China on Christmas Eve. The state-run Korea Central News Agency did not identify the man, who it said was "now under investigation by a relevant organ."
At the time, U.S. State Department spokesman Ian Kelly said Washington was concerned by reports that the missionary, Robert Park, had gone into North Korea, but could not confirm them. Washington and Pyongyang have no diplomatic relations, but Kelly said the Swedish Embassy -- which looks after U.S. interests in North Korea -- was trying to learn more.
Park told relatives before Christmas that he was trying to sneak into the isolated communist state to bring a message of "Christ's love and forgiveness" to North Korean leader Kim Jong Il. In a written statement issued on the family's behalf, his brother, Paul Park, said in late December that Park's well-being "has been a source of ongoing concern and anxiety" since they received reports that he had entered North Korea.
North Korean authorities take a dim view of people who enter the country without authorization. Two American journalists who were arrested along the North Korean-Chinese border in March faced a 12-year sentence of hard labor, but were released after a meeting between Kim and former U.S. President Bill Clinton in Pyongyang.
But Park's parents told CNN affiliate KFMB in December that their son was willing to risk his life to deliver his message to Kim.