A North Korean spy has been caught impersonating a defector from the North, the South's public security authorities said Saturday.

The man was identified as a member of the North's Military Security Command in a routine investigation of newly arrived defectors, government agencies, including the National Intelligence Service, said.

The man entered South Korea in April by way of China, Laos, Vietnam and Thailand, in an apparent effort to seem like a defector seeking to resettle in the South, the authorities said.

"But he did not engage in any actual spying activity because he continuously underwent questioning after coming to the country," a spy agency official said on condition of anonymity. 

"He has received no detailed instruction from the North, yet."

The authorities will continue their investigation, viewing it as highly likely the man has links to other North Korean posing as defectors to the South.

(Yonhap News)