Britain's Civil Aviation Authority said flight bans had been lifted late Tuesday after a reassessment of risks.

British Airways said on its website it was planning to operate long-haul flights from Heathrow and Gatwick airports in London. The carrier reminded passengers that since "many aircraft and crew (are) out of position, it will still take some time to return to our full flying programme."

The Icelandic Meteorological Office said Wednesday that the volcano under the Eyjafjallajoekull glacier was spewing only a little smoke and ash. The smoke plume was reaching a height of three km, compared with 11 km a few days ago.

Winds were also blowing the ash more to the north, it said.

The volcano erupted a week ago, causing major disruptions to European air traffic and intercontinental flights.

Australia's Qantas Airways said it would take "some weeks" to clear the 15,000 of its ticket-holders delayed by the eruption.

Thai Airways International reopened its regular flights to Zurich, Switzerland while many other routes to Europe remained closed.

Early Wednesday, airspace was reopened in Denmark and planes could start using Copenhagen Airport, the largest hub in the Nordic region.

Finland also reopened most of its airspace and Norway also expected its airspace to remain open.

Sweden's southern airspace including Stockholm airport, the main hub, was closed Tuesday evening until Wednesday afternoon.

Most flight restrictions had also been lifted in Germany Wednesday, with its major airports allowed to operate normally. However, some secondary airports remained under restriction.

Flights across Europe had been suspended for fear that the volcanic dust could turn into a glassy substance inside jet engines, damaging them.

Airlines are now working to clear the backlog of hundreds of thousands of passengers stranded at airports around the world. Tuesday, three quarters of Europe's airspace had been reopened, the European air safety authority Eurocontrol said.