Britain's skies have reopened as an airline boss branded the latest ash cloud no-fly zones a "gross over-reaction".

But before restrictions were lifted air passengers suffered more travel misery as the Icelandic volcanic ash cloud grounded planes.

Hundreds of flights had to be cancelled or delayed on Monday morning, with Heathrow and Gatwick among the airports affected.

By 1pm all but the most northerly Scottish island airports were operating normally again as the threat moved away.

But delays continued, with some long-haul flights due in at Heathrow on Monday not expected to arrive until early Tuesday.

British Airways chief executive Willie Walsh said blanket bans on flying were "a gross over-reaction to a very minor risk".

He said: "I am very concerned that we have decisions on opening and closing of airports based on a theoretical model. There was no evidence of ash in the skies over London today yet Heathrow was closed."

Mr Walsh said safety of passengers and aircraft was paramount. But he added that "a much better and more sensible" approach to dealing with the ash problem needed to be adopted.

Chris Browne, managing director of Thomson Airways, said: "Safety is and will always remain our number one priority. However it is our view that if the ash clouds are to continue, current modelling needs to become more accurate and there needs to be greater clarity for the industry on operational parameters.

"It is vital that we understand the tolerance levels for aircraft and engines in particular, but also gain a better knowledge of the predictability of the ash clouds."