For about an hour last night people visiting the site found themselves redirected to a different site carrying a message from the Iranian Cyber Army.
The message read: "Iranian Cyber Army THIS SITE HAS BEEN HACKED BY IRANIAN CYBER ARMY iRANiAN.CYBER.ARMY@GMAIL.COM.
"USA Think They Controlling And Managing Internet By Their Access, But They Don't, We Control And Manage Internet By Our Power, So Do Not Try To Stimulation Iranian Peoples To....
"NOW WHICH COUNTRY IN EMBARGO LIST? IRAN? USA? WE PUSH THEM IN EMBARGO LIST ;) Take Care."
Twitter said its Domain Name System (DNS) records were "temporarily compromised" and it was looking into the issue.
There is no information available on the group, but Twitter has history with Iran. It was used by Iranian opposition supporters to mobilise in the wake of the widely questioned Iranian presidential election that saw Mahmoud Ahmadinejad returned to power.
However, it was also used by Iranian internal security to monitor and attack protestors. At one stage conspiracy nuts were accusing Israel of harnessing Twitter to bring down the Iranian regime.
TechCrunch reports that at least one other website mawjcamp.org, an Iranian reformist website based outside of Iran, had also been hacked, suggesting the work was by people within the Iranian regime.
Twitter has suffered a string of problems relating to hackers. In July, TechCrunch was passed a series of internal documents such as revenue predictions by a hacker.
In January, Twitter suffered another attack after hackers posted fake messages to the accounts of 33 Twitter users, including those of Fox News, the campaign of President-elect Barack Obama, CNN anchor Rick Sanchez, and Britney Spears.
The microblogging service has also been blighted by phishing scams where scammers have sent bogus direct messages to gain access to users' accounts for spam purposes.