Global news network the Associated Press reported today, that hackers have attacked dozens of South Korean government and private web sites, sending a warning that the country's computers are under grave threat.

As per the AP report, South Korea's National Cyber Security Center said they had seen signs of a "denial of service" attack, in which large numbers of computers try to connect to a site at the same time, in an attempt to overwhelm the server.

In a statement, printed in the AP news, a top South Korean cyber security company, AhnLab, said that the targets included websites at South Korea's presidential office, the Foreign Ministry, the National Intelligence Service, U.S. Forces Korea, and some major financial institutions. However, the Korea Communication Commission reported no immediate damage to its websites.

Park Kun-woo, a spokesman for AhnLab, said the attacks were similar to ones that have targeted South Korean websites in the past, in that they were denial of service attacks and largely targeted the same sites, wrote Kay Seok, an AP reporter based in Seoul, Korea.

According to AhnLab, a computer user discovered a bug in their system on Thursday night. After analyzing the bug, AhnLab found malicious software designed to attack web sites and warned the targets in advance to prepare for such an attack. Consequently, stated Kun-woo, the damage was not huge. It resulted only is a brief slowing of some of the websites. Meanwhile, AhnLab is helping those infected with free software to repair the infected computers.

While the previous denial of service attacks on South Korean government web sites were traced to China, it was not immediately clear where Friday's attack originated.

In 2009, cyber attacks on South Korean sites were blamed on North Korea. However, expert analysis and investigation led to no conclusive evidence that North Korea was responsible. South Korean media reports indicate that North Korean government is operating an Internet warfare unit—aimed at hacking U.S. and South Korean military networks, wrote AP.