UN Secretary-general Ban Ki- moon called on the Democratic People's Republic of Korea (DPRK) on Thursday to release a U.S. man arrested in December for illegal entry, according to the UN spokesperson's office.

Ban hopes the DPRK will release Robert Park "on humanitarian considerations responding to the repeated calls by his family and the international community," said UN spokesperson Martin Nesirky.

"A U.S. citizen illegally entered the country across the North Korea-China border and has been detained. The person is currently undergoing questioning by a related agency," the official KCNA news agency had reported.

In Washington, the U.S. State Department is aware of the situation as is Ban, who has been following the case closely, said Nesirky.