Civil aviation officials say a drifting, dense cloud of volcanic ash is "rapidly encroaching" on British airspace and is forcing the closure of airports in Northern Ireland.
The National Air Traffic Service said Sunday that a no-fly zone has been imposed over parts of Northern Ireland, and no flights are going in or out of airports in Belfast or the Isle of Man. Dublin and Shannon airports in the Republic of Ireland will stay open until 1 pm (1200 GMT).
Britain's Department of Transportation has warned that different parts of the country's airspace, including England's southeast, home to Europe's busiest airport at Heathrow, could close at different times through the next few days because of the eruption of Iceland's Eyjafjallajokul volcano.