Japanese police say they have identified two computer servers and a personal computer in Japan that were used in a massive cyber attack on South Korean government offices six months ago.

The National Police Agency said Thursday it was the first known instance of a personal computer in Japan being used for cyber terrorism. They said they believe the two servers and the personal computer were remotely accessed without the knowledge of their owners.

South Korean officials say a total of 746 computers from 70 countries were used in the denial-of-service attack, in which a flood of requests overwhelmed government websites. North Korea is suspected of originating the attack, in which the South Korean president's office and defense ministry were among the targets.

Japanese police say the two servers and the personal computer in Japan were found to be infected with a virus that made it possible for them to be manipulated from the outside.

They said all three were running older operating systems without anti-virus software. The owners have been advised to improve their computer security.