Twitter has been hit by a embarrassing security breach.
A group claiming to be Iranian Cyber Army managed to redirect Twitter users to its own site displaying a political message.
Twitter said the attack had been carried out by getting at the servers that tell web browsers where to find particular sites.
The site said it would start an investigation into what allowed the "unplanned downtime" to take place.
Twitter was hit by the security breach at 2200 PCT (0600 GMT) which led to users being redirected to a page showing a message declaring it had been hacked by the Iranian Cyber Army.
