ABU DHABI - Heavy fog disrupted flights in and out of Abu Dhabi airport for hours early Sunday, with many outgoing flights cancelled and incoming ones diverted to other airports such as Dubai.

The disruption started shortly after midnight and lasted until around 6:00 am, said Etihad Airways, the national carrier of the United Arab Emirates (UAE).

"Flights into Abu Dhabi this morning were diverted to other airports in the region due to un-forecast fog," Etihad said in an e-mailed statement.

The dense fog, which rolled in just after midnight, delayed the departure of 44 early morning flights by up to four hours from Abu Dhabi, while several others were cancelled, the statement said.

Delays were anticipated for the rest of the day.

Dense fog occurs in the desert state on an irregular basis and disrupts flights, especially during the "cooler" autumn and winter seasons when temperatures fall below 10 degrees Celsius at night.