Experts said they saw little chance of a repeat of last year's six-day closure of airspace, which also hit trans-Atlantic flights, when another Icelandic volcano erupted, although airlines have been warned the new ash cloud will drift.

So far Iceland, particularly the towns and villages to the south and east of the Grimsvotn volcano, have suffered most. Day turned into night when a thick cloud of ash descended on the area, smothering cars and buildings.

The cloud had also begun to drift over the capital Reykjavik by late Sunday evening and the civil aviation authority said the prospects for re-opening the main international airport on Monday were not good.

Europe's air traffic control organisation warned on its website that ash could spread southwards.

"Ash cloud is expected to reach North Scotland on Tuesday 24th May. If volcanic emissions continue with same intensity, cloud might reach west French airspace and north Spain on Thursday 26th May," it said in a traffic bulletin.

Iceland's meteorological office said the plume from Grimsvotn, which last exploded in 2004, had fallen to 10 to 15 km in height from a peak of 25 km (16 miles).

But the eruption was much stronger than the one at a volcano further south last year which closed European airspace and halted trans-Atlantic flights, due to worries that particles could get into aircraft engines and cause accidents. The airline industry said it lost $1.7 billion in revenues.

"It could lead to some disruption, but only for a very limited time and only over a very limited area," said University of Iceland Professor of Geophysics Magnus Tumi Gudmundsson.

"We see some signs that the (eruption's) power is declining a bit, but it is still quite powerful," he said, adding that the eruption was the most violent at the volcano since 1873.