According to press reports, around 30 North Koreans based in Northern China created programs that could breach servers for online game such as 'Lineage' and 'Dungeon and Fighter'.

This allowed unmanned PCs to play the games around the clock, collecting points which could be exchanged for cash at Web sites. The software was also sold, according to police.

In less than two years the gang made around $6 million, of which just over half was given to the North Korean hackers, who are said to all be graduates of the country's top science universities. Some of the money then made its way back to the North Korean government.

The five South Koreans arrested are charged with creating and distributing illegal computer programs to clients in China and South Korea. Another 10 people are being investigated in connection with the scam.