Twitter under attack by 'mouseover bug'

Computer security firms said thousands of users, or more, were affected by the bug, which appears to send out or "re-tweet" messages simply by rolling over an infected link with the computer mouse.

Those hit by the bug included Sarah Brown, the wife of the former British prime minister who has over one million followers on Twitter, and White House press secretary Robert Gibbs.

"My Twitter went haywire - absolutely no clue why it sent that message or even what it is... paging the tech guys," Gibbs wrote on @presssec.

Twitter said it had identified the attack and was working on a solution.

"We expect the patch to be rolled out shortly and will update again when it is," the San Francisco-based service said a brief statement on its website.

Security expert Graham Cluley of computer security firm Sophos said the bug only affected users of the Twitter.com website not third-party programs developed to access the popular microblogging service.