Seoul. South Korea has issued a cyber attack alert after hackers penetrated a number of official websites, including the presidential "Blue House” website, on the anniversary of the start of the Korean War."The government can confirm a cyber attack by unidentified hackers that shut down several sites including the Blue House,” the science ministry said in a statement released on Tuesday, adding that the five-stage national cyber alert had been raised from level one to two.A number of news media websites and several government agencies, including the office for Government Policy Coordination and the ruling New Frontier Party, were also affected by what seemed to be a coordinated attack beginning at 10:45am local time (01:45 GMT).War anniversaryThe hacking coincided with the 63rd anniversary of the start of the Korean War on June 25, 1950. The two countries are technically still at war, as the conflict ended with an armistice rather than a peace treaty. The ministry statement did not speculate on who might be responsible. Investigations into several recent large-scale cyber assaults on South Korean media groups and financial institutions concluded that they originated in North Korea.