A South Korean court on Friday acquitted a North Korean defector of carrying out espionage activities for the communist regime.

The Seoul Central District Court delivered the not-guilty verdict to the 40-year-old defendant, only identified by his surname Hong, citing a lack of credibility in the evidence.

Upon receiving the verdict, Hong was immediately released.

The court said Hong was questioned by investigators led by the National Intelligence Service without a lawyer present, which is in violation of the country's criminal procedure law.

"The court does not acknowledge the evidence since the testimony was drawn up without following standard procedure," Judge Kim Woo-soo said in his ruling.

Hong was indicted on charges of trying to kidnap a broker who helped North Koreans escape the communist country in June 2012, according to prosecutors.

Prosecutors allege that Hong belonged to the Defense Security Command of the Korean People's Army, which oversees espionage operations against the South.

Hong was further charged with spying on the activities of defectors living in the South, after entering the country by falsely disguising himself as a North Korean defector, prosecutors said. (Yonhap)