Aviation authorities in the Irish Republic said on Monday that flights in and out of Ireland will be banned because of possible risks from volcanic ash.

The fresh restrictions will apply from 0600 to 1200 GMT on Tuesday.

"Ireland falls within the predicted area of ash concentrations" that exceed acceptable levels, the Irish Aviation Authority (IAA) said.

However, the IAA said over-flights from the United Kingdom and continental Europe would not be affected.

The decision had been made after the Volcanic Ash Advice Centre (VAAC) said a plume of ash from a volcano in Iceland was drifting towards Ireland. But IAA Chief Executive Eamon Brennan said he was hopeful the flight restrictions could be eased later on Tuesday.

Britain's Civil Aviation Authority (CAA) also said earlier Monday that the airspace over Scotland's Outer Hebrides would be closed, according a BBC report.

Flights over Europe were banned for six days last month because of fears of the effect of volcanic ash on jet engines, causing losses of billions of dollars to airlines in Europe.