Ryanair flies plane through Grimsvotn volcano ash cloud (VIDEO)

Irish budget airline Ryanair, which objects to restrictions placed on airlines arising from the eruption of Iceland's Grimsvotn volcano, has flown a plane safely though the thickest part of the volcano's ash cloud.

Ryanair said it had completed a one-hour ''verification flight'' up to 41,000 feet in Scottish airspace Tuesday morning, the Telegraph reports.

In a statement, a spokeswoman for the airline said: ''There was no visible volcanic ash cloud or any other presence of volcanic ash and the post-flight inspection revealed no evidence of volcanic ash on the airframe, wings or engines.

''The absence of any volcanic ash in the atmosphere supports Ryanair's stated view that there is no safety threat to aircraft in this mythical 'red zone', which is another misguided invention by the UK Met Office and the CAA [Civil Aviation Authority].

''Ryanair has also received written confirmation from both its airframe and engine manufacturers that it is safe to operate in these so-called 'red zones' and, in any event, Ryanair's verification flight this morning also confirms that the 'red zone' over Scotland is non-existent.'' 

However, U.K. Transport Secretary Philip Hammond told the BBC that the information he had seen regarding the Ryanair flight suggested it "did not actually fly in any areas" where ash was expected. He added that a Loganair plane which flew today had "encountered some light ash"

Thousands of U.K. passengers were facing travel delays Tuesday as airlines canceled flights as the cloud of ash from Grimsvotn headed toward Scotland.

The cloud — deemed potentially hazardous to aircraft by flight safety experts — also changed the travel plans of U.S. President Barack Obama, on a European tour.

The eruption of Grimsvotn has sparked fears of a repeat of last year’s shutdown of European airspace after another Icelandic volcano spewed plumes of ash into the sky, raising concerns that volcanic ash could damage aircraft engines.

Obama, who is on a six-day European tour, left Ireland for Britain on Monday night — a day ahead of schedule — because of concerns the volcanic ash cloud could affect travel on Tuesday, the Associated Press reports.

About 400 passengers spent the night at Edinburgh airport. A Scottish regional airline, Loganair, has canceled 36 flight services, while British Airways, KLM, Aer Lingus and EasyJet have all suspended flights headed for northern Britain.

But Ryanair, the Ireland-based budget airline, objected to an order from Irish air safety officials to ground its Tuesday morning flights to Scotland, called the cancelations “unnecessary,” the BBC reports.

"Ryanair strongly object to this decision and believe that there is no basis for these flight cancelations and will be meeting with the [Irish Aviation Authority] on Tuesday morning to have this restriction on Ryanair flights removed as a matter of urgency,” a statement on Ryanair's website said.

Experts have said that the ash from the Grimsvotn eruption, which began Sunday, appears to be coarser than the fine ash from last year’s eruption of Eyjafjallajokull, and therefore should fall to the ground faster and not travel as far, AFP reports.

The ash cloud is not due to reach other parts of the U.K. until later this week. Asian airlines said that flights to Europe were operating as normal but they were monitoring the situation, Reuters reports.

"The low-level winds are … blowing strongly towards the U.K.," Peitur Arason of the Icelandic Meteorological Office, told Agence France-Presse.

This year, the decision on whether or not to fly is up to individual airlines in the U.K., although they still have to receive final approval from the Civil Aviation Authority.

The U.K. transport secretary told the BBC that the country was "better" prepared than it had been in 2010, with “much more robust systems” to minimize the disruption caused by volcanic ash clouds.

"Most importantly, the basic situation now is that the threshold for most aircraft is 20 times where it was last year,” Philip Hammond said. “We have got from 200 micrograms per cubic meter to 4,000 micrograms per cubic meter as the threshold up to which most aircraft can fly."

But he also warned that travelers must learn to live with disruptions caused by volcanic activity in Iceland.

See a map of the volcanic ash cloud.