Korea's prosecution said Friday that it detained five Koreans on charges of spying for North Korea by forming an underground anti-state organization.

The Seoul Central District Prosecutors' Office said five locals were imprisoned on suspicions of violating the country's national security law as they allegedly set up an anti-state organization, ordered by North Korea's ruling Workers' Party.

A 48-year-old chief executive at a tech firm, known by his surname Kim, was suspected of spearheading the anti-state group after being won over by North Korean agents, according to the prosecution.

Kim is suspected of collecting and delivering information about Korea for several years to the North and contacting spies residing in Japan or other North Korean senior agents when he stayed in foreign countries. Kim is denying the charges, the prosecution added.

Sources said the South's intelligence authorities are investigating several figures in the academic and political circles on suspicions of espionage. The probe could have significant repercussions as former or incumbent political figures in opposition parties are said to be on the list. (Yonhap News)