Renewed and more intensive ash eruptions from Iceland overnight could cause delays to transatlantic flights, European air traffic control authorities have said.

Plumes from Iceland's Eyjafjallajokull volcano are continuing to spread across the Atlantic sea, says Eurocontrol, into the path of the busy transatlantic air corridors between Europe and the US.

"Transatlantic flights are being re-routed south of the affected area which could cause delays to these flights," Eurocontrol said in a statement.

Transatlantic air passengers face the threat of delays this weekend as a substantial volcanic ash cloud drifts between Europe and the US.

Airports in western Ireland were temporarily closed this morning as the latest Icelandic eruption pushed a smoke plume into busy transatlantic air routes.

The Irish Aviation Authority said flights had been diverted around the cloud, which could stretch from Iceland to the tip of northern Spain by tomorrow, but a wind change from a north-westerly direction to north-easterly could push the ash over mainland Europe. "If the wind … moves in a north-easterly direction we are in trouble, not just in Ireland and the UK but also northern Europe," the IAA said.

The Civil Aviation Authority said transatlantic flights to and from UK airports were being rerouted, but suffering minor delays to journey times as a result. "It is not anticipated that it will result in flights being cancelled or severe delays," the CAA said. It added that there were no forecasts of a wind change that would alter the direction of the cloud, which is about 1,250 miles long and 800 miles wide. "It means that flights have to take slightly different routes," it said.

Eurocontrol, the Brussels-based air traffic controller, said some European flights could take one or two hours longer.

The CAA said this week that activity at Iceland's Eyjafjallajokull volcano raised the threat of further flight delays and cancellations this summer, despite new regulations that permit flying through ash-contaminated airspace, where none was allowed previously. The latest ash cloud, however, breaches new safety parameters set by aircraft engine manufacturers.

Scottish and Northern Irish airports were closed temporarily this week. European airspace was shut for six days last month at a cost of over £1bn to airlines.

Just nu råder zon 1, det vill säga flygförbud, i nordligaste Spanien, norra Portugal, väster om Irland och sydligaste delarna av Franrike.

– Även Skottland kan komma att påverkas av zon 1, säger Björn Stenberg vid Luftfartsverkets pressjour till Aftonbladet.

Enligt TT har hittills 673 flygningar ställts in i Spanien och 104 i Portugal.

– I natt kommer askan att gå in över Italien där det förmodligen kommer att innebära zon 2, det vill säga att vissa får flyga med tillstånd, säger Björn Stenberg.

Samtidigt har flera transatlantiska flygningar mellan Europa och USA försenats.

– Askan ligger på så pass hög höjd att man måste flyga runt. Tidigare kunde man flyga över askan, men nu är den uppe på 11 500 meter.

Enligt TT har ett 60-tal invånare i området kring Eyjafjallajökull på Island frivilligt gett sig av efter torsdagens utbrott.

– Det faller en massa aska i omgivningarna, sade Gudrun Johannesdottir från civilförsvaret till AFP.

Ingen har dock tvingats evakuera, rappoterar TT.