Twitter users once again experienced the unpleasant side of Web 2.0 over the weekend as the popular microblogging site was hacked and messages were sent out over users' feeds encouraging visitors to follow a potentially malicious link.

Over 700 accounts were compromised, allowing the hacker to post the following message and related link in their feeds: "hey! 23/Female. Come chat with me on my webcam thingy here".

According to Rik Ferguson, solutions architect at security vendor Trend Micro, the link takes users to a porn webcam portal which "looks to have been designed with credit card harvesting in mind".

In a posting on the Twitter blog, the firm said it had reset the passwords of any compromised accounts and "removed the spammy updates". It advised users to always choose strong passwords and to avoid sharing passwords with untrustworthy sites.

It's still unclear how the user accounts were hacked in the first place, although some commentators have pointed to a similar attack about a month ago.

"You don't have to be Albert Einstein to put two and two together, and deduce that these attacks must be related," wrote Sophos senior technology consultant Graham Cluley in his blog.

"We're seeing more and more attacks from spammers, phishers, malware authors, scammers and identity thieves against the users of social networks like Twitter and Facebook. These aren't just proof-of-concept attacks in controlled conditions - they're full-blooded assaults seen in the wild every day, making money out of real people."