According to reports, the South Korean National Intelligence Service (NIS) and National Police Agency arrested the suspect, said to be in his 40s, in June.
The man allegedly entered South Korea at the order of North Korea’s spy agency.
It is unclear of the circumstances of the suspects capture while further details have not been released.
Although his mission is yet to be uncovered, it is thought he was attempting to infiltrate the south’s Buddhist scene as a monk.
Local media reported how the suspect had entered the country a few years ago.
He is then said to have re-entered South Korea under a fake nationality.
But intelligence committee leader Lee Hye-hoon told reporters before a meeting: “We are not in a situation to brief information on the spy sent by North Korea.”
Authorities said it was the first espionage case in South Korea in nine years.
In other news, it has been claimed Huawei secretly helped build North Korea's mobile phone network.
The construction of the network would potentially be in violation of sanctions aimed at pressuring the regime to stop developing nuclear weapons.
According to documents, Huawei partnered with China's state-owned Panda International Information Technology on projects in North Korea for nearly ten years.
In a statement responding to the report, Huawei said it currently “has no business presence” in the hermit state.