Prosecutors have demanded 20 years of imprisonment plus ten years of activity restrictions for North Korean spy Jeong Kyung-hak.

In the final trial on Friday, prosecutors underlined the seriousness of the case as the defendant had been dispatched directly by North Korea.

The defendant's legal counsel said that Jeong never committed any destructive acts and sent only the usual photos to North Korea.

Jeong was indicted on charges of infiltrating South Korea three times between March 1996 and January 1998. He is suspected of taking pictures of sensitive facilities including a nuclear power plant in Ulsan, an Air Force radar base in Cheonan and the U.S. military base at Seoul's Yongsan.