The ash cloud is now expected to move towards south-eastern France
A cloud of volcanic ash from Iceland has forced airports in North Africa to shut for the first time, as well as hitting air travel in southern Spain.
Morocco halted flights from Rabat, Casablanca and at least three other airports while, at one point, seven airports in Spain were closed.
Turkey banned flights over its north-west for four hours from 1200 GMT.
Ash said to be drifting towards south-east France is at high altitude and is not expected to affect airports there.
Eurocontrol, the European air traffic control agency, said it expected 29,000 flights to take to the air on Tuesday, which is close to normal for this time of year. On Monday, there were 29,155 flights.
Icelandic volcanologists say the ash over Europe this week is left over from previous weeks and can travel around in the atmosphere carried by winds.
"We really don't know when it will settle down," said Bjorn Oddsson of the Institute of Earth Sciences at Iceland University.
"So even if the volcano stops, we can look at this problem for a couple of weeks after," he was quoted as saying by AFP news agency.
In the UK and Ireland, rules governing air safety during the volcano crisis were eased by the Civil Aviation Authority, the UK safety regulator.
It said it had lifted the 60-mile no-fly buffer zone imposed around dense areas of ash cloud, clearing the way for more flights.
In Morocco, the airports in Tangier, Tetouan and Essaouira were also closed. According to AFP, eight Moroccan airports in all shut down on Tuesday.
Volcanic ash cloud disrupts air travel again
Prior to Tuesday, the ash had only affected European airports.
In Turkey, Istanbul's international airport remained opened despite the flight restrictions.
Spain reopened both of Tenerife's airports along with La Gomera and Badajoz after a temporary closure, but La Palma, Seville and Jerez remained closed as of Tuesday afternoon.
Overflight restrictions at altitudes between 6,000m (20,000ft) and 10,500m (35,000ft) remained in place, with transatlantic flights mainly affected.
At the weekend, 19 airports were shut in the north of the country because of ash fears.
Most of the ash cloud is above the Atlantic now, meaning transatlantic flights are longer and there are many delays as pilots fly around the hazard, the BBC's Sarah Rainsford reports from Madrid.
It is almost a month since the volcano in Iceland first erupted, closing airspace across Europe for almost a week and stranding hundreds of thousands of travellers.
The budget airline Easyjet alone had to cancel more than 6,500 flights. It has announced that the disruption cost it up to £75m ($110m) and is now seeking compensation from governments.
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