Thousands of passengers face UK flight cancellations because of drifting ash from an Icelandic volcanic¹ eruption².

冰岛某火山爆发，空中漂浮的灰尘可能使数千英国游客被迫滞留机场。

BA, KLM, Aer Lingus and Easyjet are among the airlines that have chosen to suspend services in and out of Scotland for the coming hours.

But Ryanair has objected to an order from Irish officials to ground its morning flights to and from Edinburgh, Glasgow and Aberdeen on safety grounds.

The ash cloud is not due to reach other parts of the UK until later this week.

Ryanair said it would be complaining about the "unnecessary cancellations".

A statement on Ryanair's website read: "Ryanair strongly object to this decision and believe that there is no basis for these flight cancellations and will be meeting with the [Irish Aviation Authority] on Tuesday morning to have this restriction³ on Ryanair flights removed as a matter of urgency（紧急） ."

The cancellations come just over a year after another volcanic eruption in Iceland caused widespread disruption across Europe, including the closure of UK airspace, amid concerns about the damage volcanic ash could cause to engine aircraft.

This year, in the UK, the decision on whether to fly or not in ash cloud conditions is down to individual airlines, although they have to apply to the Civil Aviation Authority (CAA) for final approval.

The transport secretary said the UK was "better" prepared than it had been in 2010.

Philip Hammond told BBC Two's Newsnight there were now "much more robust⁴ systems" in place to "minimise the disruptive effect" and there was now a better understanding of the risk from ash clouds.

"Most importantly, the basic situation now is that the threshold（门槛，极限） for most aircraft is 20 times where it was last year. We have got from 200 microgrammes per cubic metre to 4,000 microgrammes per cubic metre as the threshold up to which most aircraft can fly."