WASHINGTON (AP) — State Department email service has been restored after a nearly 12-hour worldwide outage hit its entire unclassified system.

Department spokeswoman Heather Nauert said service resumed slowly shortly after midday Friday and was expected to be completely restored by late afternoon.

The outage began around 2 a.m. Friday morning and officials said it was not caused by human error and not "any external action or interference."

The department was forced to shut down its unclassified email systems in 2014 in what officials said at the time was routine maintenance. But it later emerged that the system had been compromised by hackers believed to be affiliated with Russia and that the maintenance explanation was a cover story.