Border guards from the Republic of Korea arrested a US citizen who they believe was attempting to swim across the border into the Democratic People's Republic of Korea, a defense official said on Wednesday.

The man was arrested on Tuesday night at a river near the Demilitarized Zone, part of a restricted military area, the official said, speaking on condition of anonymity.

He said investigators are questioning the man about the purpose of his apparent attempt to enter the DPRK but gave no further details.

Yonhap News Agency, citing an unidentified government source, reported that the man was in his late 20s or early 30s and told investigators that he tried to go to the DPRK to meet leader Kim Jong-un. ROK marines guarding the Han River, which flows into an estuary and meets the DPRK's Imjin River, found the man lying on the riverbank, apparently suffering from exhaustion, the report said.

The US embassy in Seoul said it had been in contact with ROK authorities about the report.

Last year, ROK soldiers shot and killed a man with a ROK passport who officials said ignored warnings to return to the country after trying to enter the DPRK via a border river.

AP-Reuters