Ash from a volcano eruption in Iceland has prompted aviation officials to restrict flights over parts of Norway and the United Kingdom.

Norway's aviation authority AVINOR closed roughly the northern half of the country's airspace on Wednesday evening, from Trondheim to the north. And U.K. air traffic control provider NATS said early Thursday it was restricting flights in northern Scotland.

NATS warned the ash cloud is expected to move south, hinting that the flight-restriction zone could expand.

Some Norwegian flights were canceled or delayed because of the airspace closure, according to information from AVINOR's Web site.

The ash cloud came from an eruption of a volcano beneath Iceland's Eyjafjallajokull glacier early Wednesday. The eruption - the latest in a series that began on March 20 - blew a hole in the mass of ice.