Flights across northern Germany have been grounded because of ash from Iceland’s Grimsvotn volcano.
Bremen and Hamburg airports closed early on Wednesday, with traffic at Berlin’s airports also halted later in the morning.
But air traffic is returning to normal in other parts of northern Europe, a day after about 500 flights were cancelled across the region.
Europe’s air traffic control body Eurocontrol said no flights were expected on Wednesday at Bremen and Hamburg airports, which on a normal day handle about 120 and 480 flights respectively.
Eurocontrol said the cloud could also affect parts of Poland. There are no restrictions on flights in any other part of Europe.
Experts say particles in the ash could cause jet engines to stall.
Germany’s rules regarding flying through volcanic ash are tighter than the rest of Europe. But the head of the country’s airport organisation said Europe-wide rules were needed.
France’s civil aviation authority has said it expects very little disruption to air traffic and was not expecting to close any of the country’s airspace.
Air traffic in Norway, Denmark and the UK was disrupted on Tuesday, with Scotland, Northern Ireland and northern England especially badly hit.
But Britain’s weather service said the concentration of volcanic ash in UK airspace would decrease significantly over the course of Wednesday.
The volcano began erupting last Saturday, sending clouds of ash high into the air.
The ash particles from Grimsvotn are larger than those from Eyjafjallajokull, and so fall to the ground more quickly. Therefore less disruption is expected.
European Union transport commissioner Siim Kallas said: “We do not at this stage anticipate widespread airspace closure and prolonged disruption like we saw last year.”
The Met Office said however that if Grimsvotn volcano continued to erupt at “current variables”, much of the country could be affected by ash on Friday, with flights being potentially disrupted.
A forecaster at Iceland’s meteorological service said Grimsvotn was producing less ash on Tuesday and the plume had decreased in height to about 5,000m.