"We are working to recover from an unplanned downtime and will update more as we learn the cause of this outage," Twitter stated in an update on it status page.
A later update from the microblogging service indicated the hackers managed to tamper with the site's Doman Name Service records.
"Twitter's DNS records were temporarily compromised but have now been fixed. We are looking into the underlying cause and will update with more information soon," Twitter stated.
The hackers managed to deface Twitter's home page, as users attempting to reach the service in the early hours Friday were greeted with a message that stated the sabotage was perpetrated by a group that called itself the Iranian Cyber Army.
"This site has been hacked by the Iranian Cyber Army," the message stated.
The group was previously unknown, raising the possibility that the incident was in fact carried out by pranksters, rather than a cadre of cyber criminals with links to Iran's anti-West political authorities.
It was not immediately clear if intelligence officials in this country planned to investigate the breach.
The attack comes just a day after the Wall Street Journal reported that Middle Eastern terrorists had managed to hack into live video feeds from the unmanned Predator attack drones. However, there was no apparent connection between the incidents.
Twitter has suffered numerous outages in the past, but most have not lasted more than a couple of hours.
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