Ryanair yesterday cancelled its Edinburgh-Malta-Edinburgh service as planes remained grounded in most Scottish airports because of a rise in volcanic ash levels.

The morning flight from Edinburgh, due to land just after 11 a.m., and the return flight, scheduled to leave 25 minutes later, were both cancelled.

This was the second consecutive day that the low-cost carrier cancelled a flight to Malta, having called off its Dublin service on Tuesday.

No-flight restrictions were imposed for a few hours at a number of Scottish airports and in the Hebrides after the Civil Aviation Authority ruled that the amount of volcanic ash in the air exceeded safety levels. Some Irish airports, including Dublin and Donegal, were also closed for some time.

The CAA said that although the ash cloud threat could reach northwestern England and Wales, it would miss London's busiest airports - Heathrow and Gatwick.

Volcanologist Bill McGuire was quoted by The Telegraph as saying that the volcano could cause further problems for up to a year.

Ash from Iceland's Eyjafjallajokull volcano caused major disruptions last month when most of Europe's airspace was closed between April 15 and 21, costing the airline industry almost €2 billion. Air Malta was forced to cancel over 200 flights during the week-long shutdown, believed to have cost the local airline hundreds of thousands of euros.

The national airline operated all its flights yesterday and a spokesman said the airspace used by Air Malta was not affected.

Transport Malta stressed that even in these extraordinary circumstances, airlines were still bound to provide stranded passengers with accommodation and meals. It said it would keep monitoring the situation and issuing updates to keep the public informed about developments.