A cloud of volcanic ash prompted airlines to cancel hundreds of flights in the U.K. and regulators have warned more cancellations are coming.

It's a situation reminiscent of the chaos caused by an eruption at Iceland’s Eyjafjallajokull volcano last year. That ash cloud prompted officials to close down European airspace for several days, stranding tens of thousands of travellers.

This time, Iceland’s Grimsvotn volcano is to blame for the travel troubles. It began burping out ash on Saturday and hundreds of flights have been cancelled in Britain since.

On Tuesday, the British weather service said the ash was concentrated over Scotland and airlines must seek permission to fly over the area. Particles in volcanic ash could stall engines and cause other damage to aircraft.

Some have criticized the British government’s handling of the issue. Irish carrier RyanAir said it sent its own planes up over Scotland and detected no ash in the atmosphere.

The International Air Transport Association has also criticized British officials for relying solely on weather service data.

But many other companies are happy to follow the safety advice.

British Airways suspended all flights between London and Scotland Tuesday morning. Other European carriers followed suit.

Eurocontrol warned up to 500 flights could be affected by the ash and British authorities have said there could be some “modest delays” for transatlantic flights.

The ash cloud shortened U.S. President Barack Obama’s trip to Ireland. He and wife Michelle left the Emerald Isle Monday --  a day early -- and an ash plume may complicate his plans to visit Poland for the second time in as many years.

Obama wasn’t able to attend the funeral of Polish president Lech Kaczynski  last year because of the Eyjafjallajokull eruption and now the Grimsvotn ash plume could threaten his plans to visit Warsaw on Friday.

With files from the Associated Press.