Tens of thousands of air passengers face disruption today because of a renewed threat of ash from an Icelandic volcano.
Ireland will shut its airports until at least 1400 CET because of the risk to aircraft engines.
Some airports in outlying parts of Scotland are expected to be affected.
Eamonn Brennan, Chief Executive, Irish Aviation Authority Chief Executive:
“The essential problem is that the ash level exceeds the acceptable manufacturer tolerance level for the engines, so the most important thing is that we have no option except for the safety grounds to impose a no fly zone in Ireland”.
Overflights of Ireland from Britain and Europe will not be affected while flights in mainland Europe will be operating normally.
Ash drifting south from Iceland wreaked havoc across European air travel last month, forcing authorities to shutdown airspace for six-days over fears of the effect of ash in jet engines.