Recent update...
UK to continue to have restrictions until at least 1300 (1pm) BST Friday.
The European air traffic control organisation has said flights could be disrupted for another 48 hours by ash spewing from a volcano in Iceland.
Eurocontrol spokesman Brian Flynn said a lack of wind in the area meant the ash cloud was "progressing very slowly eastwards" and remained "very dense".
Up to 5,000 flights could have been affected by the end of Thursday.
Planes have been grounded in the UK, Ireland, the Netherlands, Belgium, Denmark, Norway, Sweden and Finland.
France is also preparing to close its main airports.
The UK closed its entire airspace to all but emergency flights because of the risk of the ash damaging planes' engines. The restrictions are not expected to be lifted before 0700 (0600 GMT) on Friday at the earliest.
'Foreseeable future'
Eurocontrol, which covers 38 nations across Europe, said the ash ejected by the volcano underneath the Eyjafjallajoekull glacier in Iceland would continue to move in a south-easterly direction.
Based on the guidelines of the International Civil Aviation Organisation, normal air traffic control services could not be provided to flights in airspaces affected by volcanic ash, requiring the temporary suspension of air traffic, it added.
Experts have warned that the tiny particles of rock, glass and sand contained in the ash cloud could be sufficient to jam aircraft engines.
Mr Flynn, Eurocontrol's assistant head of operations, said the extent of the disruption was "greater than we've ever seen before in the EU" and warned that the problem could persist for a further 48 hours.
The meteorological situation is such that the volcanic ash is progressing very slowly eastwards but there is not a lot of wind... so it is very slow and very dense," he told the Reuters news agency.
A spokesman for the UK's National Air Traffic Service (Nats) said its airspace restriction was the worst in living memory, and that it was "very unlikely that the situation over England will improve in the foreseeable future".
The restrictions silenced Heathrow airport, the world's second busiest, and stranded tens of thousands of passengers around the world.
Norway, Denmark, Sweden, Belgium and the Netherlands all later shut down their airspace entirely, while there was also major disruption in Finland, France, Germany and Spain.
Tim Farish, who had been planning to fly from Oslo to London on business, told the BBC he had been told by the airline SAS to stay at home and not bother calling for updates.
Airspace closed:
UK
Republic of Ireland
Norway
Denmark
Sweden
Belgium
Netherlands
Partial or planned closures:
Finland (northern airspace closed till 1200 GMT Friday)
France (northern airports by 2100 GMT)
.
