The Georgian blogger targeted in a cyber attack last week that affected millions of internet users across the world has said he is determined not to be silenced.

The attack, last Thursday, was aimed at the accounts of Georgy Jakhaia, who writes as Cyxymu on various social media networks, including Twitter. The denial of service (DOS) attack knocked the microblogging site offline for several hours and caused problems for Facebook and the online diary site LiveJournal.

Mr Jakhaia, 34, an economics professor, is a refugee from Sukhumi living in the Georgian capital of Tbilisi. Cyxymu is the Cyrillic spelling of Sukhumi, the rebel capital of Georgia's breakaway Black Sea region of Abkhazia.

Mr Jakhaia has become a fierce critic of Russia and last year's five-day war with Georgia, when Russia crushed a Georgian assault on South Ossetia. The attack on his blog came on the eve of the first anniversary of the war.

The professor said he had been receiving threatening letters from Russia. "It was like a special operation, an organised cyber attack on my site." He called on the Kremlin and Russian security services to investigate. "No one else but Russia was interested in destroying my site," he said.

Twitter has suffered intermittent problems for nearly a week after the initial assault. The service went down briefly on Tuesday and the co-founder, Biz Stone, said it was continuing to come under attack but added: "Our systems are looking good and the platform is healthy."

Mr Jakhaia said he was acutely aware of the media attention surrounding him, and hoped to make the most of it.

He plans to create an English-language blog to reach a wider audience. "It's really cool to be at the centre of world media interest, " he said. "After all, I have another chance to make some positive PR for Georgia, without even thinking about it."

Last Thursday's DOS attack on Cyxymu overwhelmed Twitter's servers with communications requests, taking the microblogging platform offline for several hours. Members of Facebook, the world's largest social network with more than 250 million active users, suffered delays logging in and posting to online profiles.

The assault underscored the vulnerability of Twitter's fast-growing site. Google sites were also attacked but the company managed to fend them off.