Blogging site WordPress suffered an outage after an "extremely large" DDoS attack yesterday.

The site, which hosts more than 17.9 million blogs, was unavailable for around six hours starting at 3:30pm GMT.

WordPress founder Matt Mullenweg said the attack affected all three of its data centres in Chicago, San Antonio and Dallas.

"This is the largest and most sustained attack we've seen in our six-year history. We suspect it may have been politically motivated against one of our non-English blogs but we're still investigating and have no definitive evidence yet," he said.

At around 11pm, Wordpress posted an update on its Status page that revealed the blogging service was "back to normal".

See also: WordPress 3.0 blogging software released