A massive internet attack that shut down Twitter for more than two hours Thursday and also hit Facebook, Google and LiveJournal appears to have been targeted at a blogger in the former Soviet republic of Georgia.

The blogs of several computer security firms reported that the manoeuvre included so-called distributed denial of service attacks against Twitter, YouTube, Facebook, LiveJournal and Fotki accounts owned by a man who went by the name "Cyxymu," as well as a spam attack on his Gmail account.

Cyxymu had reportedly blogged about the anniversary of a five-day conflict between Russia and Georgia that started on Aug. 8, 2008, killing 390 people and displacing thousands. During the conflict, Georgia accused Russia of launching a cyberwar against Georgian websites to coincide with military action in the breakaway Georgian region of South Ossetia.

The affected companies said they are working together to investigate what the official Twitter blog described as a "single, massively co-ordinated attack."

Facebook's Max Kelly told CNET News that they hope to find those responsible and "take action against them if we can."

The Twitter blog said the companies preferred not to speculate about the motivation behind the event. A distributed denial of service attack is carried out by "zombie" computers harnessed using malicious code to work as part of a network called a botnet.

The botnet floods particular sites with useless traffic, overloading their servers and making them inaccessible to others.

Some of the computers in the same botnet were also involved in spam attacks on Cyxymu's Gmail account, the blog for the security firm McAfee said. The spam contained links to Cyxymu's blog sites to drive more traffic there and possibly overwhelm the servers, and some falsely listed Cyxymu's Gmail account as the sender, flooding the account with automatic "out of office" notifications.

While Twitter and LiveJournal faced outages as a result of the attack, Facebook and Google were able to maintain service, although Facebook was slowed down. Most Google services were not affected, but a few users who redirect traffic from domain names they've purchased to Google-owned Blogger and other Google sites did lose the redirect for about an hour.