'The (British) server appears to have controlled compromised handler servers which spread viruses,' said Park Cheol-Soon, a network protection team leader of the government-run communications commission.
'However, it needs more investigation to confirm whether this server was the final attacker server or not.'
Seoul had previously laid the blame for the attacks - which briefly crippled major government and commercial websites - on its Communist neighbour.
But according to Park Cheol-Soon, the apparent discovery of a master server in Britain neither exonerated nor implicated North Korea.
'It does not either bolster or undermine claims that someone has done the attacks,' he said. The attacks, which involved sending multiple requests for website access from 166,000 'zombie' computers in 74 countries, crippled 14 major U.S. sites. These included the State Department, the Homeland Security Department, the Federal Aviation Administration and the Federal Trade Commission. In addition to government sites, the New York Stock Exchange, the Nasdaq electronic exchange and the Washington Post newspaper were also hit. The Korea Communications Commission downgraded its alert against the cyber attacks on Monday, saying they were 'fizzling out', and most targeted sites had normal traffic restored.