All flights in and out of the region have been suspended until at least 6pm as part of UK-wide safety precautions triggered by the southward drifting plume of dust from the eruption in Iceland.

Airlines operating out of George Best Belfast City Airport have introduced an indefinite suspension. Airport operations director Mark Beattie said while he hoped it would be back to business on Fridayhe could give no guarantee.

"At the moment all eyes are focused on the National Air Traffic Services (NATS) and the Met Office for guidance," he said. "I don't think we'll see any update or indication of weather until later.

"The suspension is indefinite at the moment. We are planning for a full day of operation on Friday and a busy one at that, but at this stage we just can't tell."

A spokesman for Belfast International Airport was also unable to give an indication when the cancellations would end.

"We apologise to passengers for any inconvenience caused but as this is an unprecedented situation, at this point we can't say when operations are likely to return to normal," he said.

The vast majority of flights in Northern Ireland had already been cancelled ahead of the NATS' noon ban on all non-emergency UK air movements, leaving many passengers stranded.

While no flights operated from or into the city airports in Belfast and Londonderry, a number of early morning departures managed to take off as scheduled from Belfast International Airport.

"This really is an unprecedented event," said Mr Beattie. "I have never experienced anything like it in my time in the business."