BBC: Icelandic volcanic ash alert grounds UK flights.
All flights in and out of the UK and several other European countries have been suspended as ash from a volcanic eruption in Iceland moves south.
Up to 4,000 flights are being cancelled with airspace closed in Norway, Sweden, Finland and Denmark among others.
The UK's air traffic control service (Nats) said no flights would be allowed in UK airspace until at least 0700 BST on Friday amid fears of engine damage.
Safety group Eurocontrol said the problem could persist for 48 hours.
The volcano is still spewing ash and the wind direction is expected to continue bringing clouds into UK and European airspace for some time to come.
The UK's airspace restriction was the worst in living memory, a Nats spokesman said. Some 600,000 people are thought to have been affected.