Ryanair has cancelled all flights to and from Glasgow Prestwick and Edinburgh Airports for the rest of the day following a direction from the Irish Aviation Authority.
Dozens of flights to and from Scotland have been cancelled todayamid safety concerns over the threat posed to aircraft engines by ash from a volcanic eruption in Iceland.
Aer Lingus has grounded 20 services while 36 flights have been cancelled by Ryanair.
The no-frills airline earlier claimed it had safely carried out a test flight through the most concentrated area of the ash cloud, and said it would continue flying.
Ryanair is disputing the methods used to detect ash by the UK's Civil Aviation Authority, hitting at the restrictions as unnecessary.
The IAA has given the go-ahead for Irish airports to remain operational until at least 3pm tomorrow afternoon, but it said some European destinations may be affected by the ash, which could impact flights to and from Ireland.
The agency will issue a further update at 9pm tonight.