JOIN USEuropean air traffic agency Eurocontrol said on Monday areas of higher ash concentration could move from over the Atlantic Ocean back toward the Iberian peninsula, threatening fresh airspace closures in Portugal and Spain.
Europe has been dogged for weeks by repeated shutdowns of air traffic since an erupting volcano under the Eyjafjallajokull glacier in Iceland started spewing ash in April.
Hundreds of flights were cancelled over the weekend after the shifting cloud sparked fresh fears of engine-clogging ash.
Italy and Germany reopened their airspace on Sunday, but restrictions were left in place in parts of Portugal, Spain, Austria and the United Kingdom. The biggest closure so far lasted for almost a week from April 15, causing about 1,00,000 flight cancellations, stranding millions of passengers. Volcanic ash is abrasive and can strip off aerodynamic surfaces and paralyse aircraft engines. It can also damage aircraft electronics.