A hacker claiming to be a member of 'UG Nazi', which has been affiliated with international hackitivists LulzSec, has claimed responsibility for the attack on Twitter yesterday (Thurs) that left the micro-blogging service unavailable for as long as 100 minutes in countries across the globe.

At 4.30pm yesterday Twitter confirmed that "Users may be experiencing issues accessing Twitter. Our engineers are currently working to resolve the issue."

The female hacker, who calls herself 'Cosmo' is said to have taken down the site with a simple DDos attack. The Telegraph have reported that Cosmo's reasons behind the attack were "mainly for the ‘lulz’, it goes to show what we are capable of.”

It is not the first time Twitter has been targeted. In its early years especially the site's servers were regularly taken down. Now hosting over 400 million tweets a day, the hacker claiming responsibility was surprised at how lax their security is.

However, Twitter have denied that the outage was due to hackers, and have claimed that the site went down due to a software fault.