One year after an Icelandic volcano brought much of Europe's air traffic to a halt, a cloud of ash from a new eruption could spread to Britain by tomorrow, causing further disruption to airlines.

Iceland's Grimsvotn volcano, in its largest eruption for 100 years, began firing ash, smoke and steam 12 miles into the sky on Saturday.

The eruption has so far affected only Iceland, which, after initially playing down developments, closed its airspace. However, all airlines flying over Europe were told yesterday to prepare for a possible spread of ash to the continent later in the week.