The government will activate an alert system against potential cyber attacks ahead of the Seoul Nuclear Security Summit on March 26 and 27th.

The alert level of "interest" will be issued on Sunday. The system is based on five levels including "normal," "interest," "attention," "warning" and "serious."

The government will monitor for cyber attacks around the clock, including hacking and distributed denial-of-access (DDoS) attacks targeting Web sites of agencies related to the nuclear summit.

Authorities are also urging people not to open e-mail messages from ambiguous senders and to update virus programs to prevent their computers from being used as zombie PCs for DDoS attacks.