LONDON: Airlines are moaning and passengers groaning as an ash-spewing Icelandic volcano is bringing misery and days of uncertainty to thousands of European air travelers. Even though some say it's been a massive overreaction by badly prepared safety regulators – one airline even claims the official scientific findings are simply wrong – hundreds of flights were canceled Tuesday as winds blew the cloud of ash from the Grimsvotn volcano over Scotland. Experts say that particles in the ash could stall jet engines and sandblast planes' windows. The only comfort for frustrated passengers and airlines is that officials in Iceland said the amount of ash being released by the volcano is decreasing, and officials don't expect the disruption to be as bad as last year, when millions were stranded after the eruption of Iceland's Eyjafjallajokull volcano. Nonetheless, British authorities said concentrations of ash in the skies over Scotland were high. “All the data we are receiving confirms our forecasts, that there is high-density ash over Scotland,” said Barry Grommett, spokesman for Britain's weather agency. But Irish budget airline Ryanair challenged the results, saying it had sent its own airplane into Scottish airspace and found no ash in the atmosphere. “Exactly as we predicted, we encountered absolutely no problems, Ryanair's chief executive Michael O'Leary said. “There's no cloud over Scotland. There's no dusting of ash on the airframe or the wings. The airspace over Scotland should never have been restricted in the first place.” Still, Ryanair was forced by Irish authorities to cancel all 68 flights in and out of Scotland for the rest of Tuesday. Seven other airlines – most of them regional carriers – also grounded their Scottish flights. The problem also affected Sweden, where 10 domestic flights were canceled Tuesday evening. The country's aviation officials say they expect medium concentrations of ash over its western coast, including over its second-largest city Goteborg. In Edinburgh, meanwhile, several hundred passengers faced either a patient wait or overnight stays in the city. “I've been told I'll get home tomorrow, but who knows,” said Kgeld Westh, an architect from Copenhagen. He was heading to a hotel in Edinburgh after his flight was canceled. Among the crowds at the airport were soccer fans heading to Dublin for the international match between Scotland and Ireland. – Associated Press No changes in Saudia scheduleABDULAZIZ GHAZZAWIJEDDAH: Saudia flights to Europe are continuing as scheduled, according to the airline's Director of Information Waleed Al-Aloumi. If a Europe-bound flight is delayed, passengers will be notified through the media, but no ash warnings have been received, he said.