Twitter has been hacked

In case you haven't heard, here's a warning going around about Twitter:

A flaw in the website of micro-blogging service Twitter is being used to pump out pop-up messages and links to porn sites.

Users only have to move their mouse over the link - not click it - to open it in the browser.

Thousands of Twitter accounts have so far posted messages exploiting the flaw including Sarah Brown, the wife of former Prime Minister Gordon Brown.

The malicious links look like a random URL and contain the code "onmouseover".

This command - written in a programming language called Javascript - automatically directs users to another website, some of which contain pornography.