The volcanic ash cloud is likely to miss London as it sweeps across the United Kingdom. However it has brought flights into and out of Scotland to a standstill, and Irish airspace has also been severely disrupted.

Ryanair chief executive Michael O’Leary has sparked controversy by claiming the cloud is “non-existent and mythical and misguided invention by the UK Met Office and the Civil Aviation Authority”.

He said Ryanair conducted a test flight 41,000ft over Scotland, which demonstrated the UK Met Office’s “red zone” forecasts were “totally unreliable and unsupported by any evidence”.

In its latest report, the Met Office said the plume was likely to head in a south westerly direction between 6pm and midnight and would probably avoid the London area.

British Airways and a host of other airlines last night cancelled all flights between London and Scotland until 2pm today, with airlines saying Scottish airspace had a “high ash concentration”.

European air traffic agency Eurocontrol said 252 flights had already been cancelled in Europe.

Air traffic control company Nats said ash is affecting Londonderry, Glasgow, Edinburgh, Prestwick, Newcastle, Carlisle, Durham Tees Valley and Cumbernauld.

This lunchtime Heathrow airport said just some flights to Iceland, Norway and Scotland were affected at the moment and there was no indication of any further disruption.

The situation is also being closely monitored by Barcelona football club whose players are due to fly to London for Saturday’s Champions League final against Manchester United at Wembley.

Despite the cancellations, experts are predicting the aviation industry will not be as adversely affected even though the eruption is 10 times the scale of the one last year.

The volcano erupted violently, and is therefore expected by vulcanologists to subside quickly. Most of the ash is blowing north.

Furthermore, following last year’s crisis, the aviation industry has a better understanding of how much ash is safe to fly through.

Transport Secretary Philip Hammond some disruption was inevitable but said a blanket ban on flights like last year would not be imposed.

He said: “We are in a much better place this year because we have worked with airlines and regulators to build a regime that puts safety first, but with far more flexibility. We will not be imposing a blanket ban like the last government.

“Instead it is up to airlines to decide whether it is safe to fly in discussions with the CAA.”

The International Air Transport Association (IATA) says it is encouraged by the improved coordination of European authorities.

Giovanni Bisignani, IATA’s Director General and CEO, said: “Work over the last year has put in place a European crisis coordination structure that is facilitating a much more effective management of this ash crisis at a working level. But Grimsvotn is also a dramatic reminder of the disappointing lack of progress at the political level on the Single European Sky.”