YouTube has removed thousands of pornographic videos from its servers following a co-ordinated attack which succeeded in uploading a catalogue of inappropriate clips to the video-sharing site.

4Chan, a bulletin board for Japanese manga content, has been blamed for the attack, which used the names of celebrities such as Hannah Montana to lure unsuspecting YouTube users to the porn videos.

YouTube's owner, Google, said thousands of videos have been deleted, but some may remain accessible for some time while the company removes the content and associated thumbnail images.

One person said to have uploaded the videos to YouTube claimed to have been part of a co-ordinated attack by 4Chan users.

"I did it because YouTube keeps deleting music. It was part of a 4Chan raid," said YouTube user 'Flonty', speaking to the BBC.Google said any YouTube account set up to attack the video-sharing site will be disabled.

However, tracking the content being uploading is a mammoth task. YouTube said in a blog on Wednesday that 20 hours of video is now being uploaded every minute. This has grown from 15 hours per minute in January 2009, and six hours per minute two years ago.