SEOUL, July 29, 2011 (AFP) - South Korean prosecutors have arrested five people on charges of spying for North Korea, a report said Friday.

The five, led by an information technology company chief identified only as Kim, were charged with violating South Korea's security law, Yonhap news agency said.

They were accused of setting up an underground communist group on the instructions of an espionage unit of North Korea's ruling Workers Party, it said.

Prosecutors were not available for comment. Espionage charges in South Korea carry a maximum penalty of death.

Kim, 48, allegedly contacted North Korean agents 10 times during trips to China, Japan and other countries from April 1994, Yonhap said, adding the detainees also included a former opposition party member.

Yonhap said authorities were investigating about 20 other people including union activists and opposition party members to see whether they were involved in Kim's espionage activities.

The South periodically detains people accused of spying for its communist neighbour.