BRUSSELS (AFP) - Travellers in Europe can expect a third day of cancelled flights Saturday, the intergovernmental Eurocontrol agency warned, as a volcanic cloud from Iceland kept planes on the ground.

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"Forecasts suggest that the cloud of volcanic ash is continuing to move east and southeast and that the impact will continue for at least the next 24 hours," Eurocontrol, which coordinates air traffic control in 38 nations, said in a statement.

"It is reasonable to assume there will be significant disruption of air traffic tomorrow," Eurocontrol spokesman Joe Sultana said from the company's headquarters in Brussels.

Eurocontrol stressed that the problem was "unprecedented" and it has called an extraordinary teleconference meeting for Monday to discuss the matter and review its coordination measures.

"Today the situation has deteriorated," said Sultana.

"It's a major and unprecedented problem in Europe. Given the exceptional nature of the impact of the ashes, Eurocontrol is taking an initiative to review, harmonize and coordinate the management," of the national air control systems, he said.

Eurocontrol expected around 12,000 flights to get off the ground on Friday, as opposed to 28,000 take offs on a normal day.

On Thursday there were just over 20,000 flights as airports around the region began to shut down as the ash cloud spread from a volcano in Iceland.

Particles from the cloud could have a catastrophic effect on plane engines.

"The experts tell us there is a real danger for aviation," from the ash getting into plane engines, Jan Pauwels, spokesman for the Belgian transport minister, told AFP.

"Air safety is of primary importance for us," he added.

Eurocontrol said airspace was currently shut down to civilian traffic in Britain (excluding Scotland), Belgium, the Netherlands, Denmark, Sweden, Norway, Finland, Estonia, the north of France including all Paris airports, northern parts of Germany, parts of Poland including Warsaw airport and the Czech Republic.

Parts of the airspace in Ireland and Sweden have reopened, the agency added.

Travellers far beyond Europe have been affected, with most transatlantic travellers also stranded.