It's become the most talked about web service in the last 6 months but experts claim that Twitter's meteoric rise could end following the second security breach in two days.

This weeks celebrity Twitter hijacks saw famous faces like President-elect Barack Obama and Britney spears' Twitter account hacked with rude and lude messages posted. This could happen to any Twitter user experts say.

On Tuesday hackers targeted 33 high profile users, including Britney Spears, American news presenter Rick Sanchez, and president-elect Barack Obama writing fake offensive or embarrassing messages from their account.

Although all messages have now been removed by Twitter staff, IT security and control firm Sophos believes that the embarrassing defacements of celebrity Twitter accounts yesterday demonstrate a worrying security problem for the micro-blogging service.

"This latest attack is actually much more serious than these people and organisations falling for a simple phishing attack. It appears that Twitter’s systems were potentially exposing everybody’s account to the danger of being taken over by hackers - this breach could actually have been much more serious and affected many more of Twitter's users”, said Graham Cluley, senior technology consultant at Sophos.

The company is calling for Twitter to "regain the confidence of its members" by making sure a similar attack doesn't happen again.

It's the second bit of bad news for Twitter this week. On Monday Twitter moved to warn users against an evolving attack, which threatens to steal personal information from them.

Clicking the links takes users to a bogus Twitter page which could steal users' login name and password and Sophos is advising users to be on their guard.