Meteorologists say an Icelandic volcano that wreaked havoc on European aviation in April has surged back to life, sending up more ash.
The Icelandic Met Office and Institute of Earth Science says a plume of ash measuring up to 7km high has been detected at the Eyjafjallajokull volcano.
The move has prompted authorities to consider re-routing trans-Atlantic flights and Ireland to shut airports for a third time this week.
The inter-governmental air traffic control agency, Eurocontrol, says the ash cloud could mean trans-Atlantic flights might need to be re-routed.
The Irish Aviation Authority (IAA) has reimposed flight restrictions at six airports between midnight and 1pm BST on Friday, though the main airport in Dublin will escape the flight restrictions.
The authority says the increased level of recent activity in the volcano in Iceland has created a massive ash cloud stretching 1600km long and 1100km wide.
Flights had been grounded in Northern Ireland, western Scotland and the far south-west of England earlier in the week, but these had now been lifted.
In April, flights over Europe were banned for six days because of fears of the effect of the volcanic ash on plane engines.
