Airspace in northern and western Europe was closed and roughly 17,000 flights canceled Friday because of the eruption of a volcano near the Eyjafjallajokull glacier, the BBC reported.
Scientists said the volcano remained active but was spewing less ash.
Airspace was closed in Britain, Ireland, Norway, Denmark, Belgium, the Netherlands, Finland and Lithuania, the British broadcaster said. Partial closures were imposed in Sweden, France, Germany, Poland, Austria and the Czech Republic.
"In general, the situation is dynamic and subject to change," the National Air Traffic Service in Britain said in a statement issued Friday.
The volcano rumbled to life Wednesday, tossing a plume of ash 7 miles into the atmosphere, melting ice and creating at least two paths of meltwater, the BBC said. Between 700 and 800 people were evacuated.
If air travel is disrupted into Saturday, Polish officials said they feared some world leaders wouldn't be able to attend Sunday's state funeral of Polish President Lech Kaczynski, who was killed in a plane crash last weekend.
Einar Kjartansson, a geophysicist with the Icelandic Meteorological Office, said ash likely would be produced at "a comparable level" for several days or weeks, The Daily Telegraph reported.
"But where it disrupts travel, that depends on the weather," Kjartansson said. "It depends how the wind carries the ash."
Health officials in Scotland said concentration of ash particles reaching the ground should not be harmful to human health..