Nats said that from 1pm to 7pm only part of Scottish airspace, including Aberdeen, Inverness and Edinburgh airports, would be available for flights in addition to airspace south to Newcastle airport.

This will mean that there will be no flights after 1pm from Glasgow, which was among the airports that was able to open earlier and operate services.

And there will be no flights before 7pm at the earliest in the rest of England, nor in Wales or Northern Ireland.

Until late Monday evening, Nats had hoped for a gradual return to something like a full service from UK airports, with the threat from the Icelandic volcano easing.

But further volcanic activity altered the situation and although a handful of flights did operate early on Tuesday from Scotland and northern England, the airport shutdown over most of the UK seems set to continue.

Nats did say that between 1pm and 7pm aircraft will be able to operate at above 20,000ft in UK airspace. This would not mean that flights could take off from Heathrow or Gatwick. But airlines could, for example, operate services from southern Europe and fly over England at more than 20,000ft before landing in eastern Scotland.

Nats said: “The situation regarding the volcanic eruption in Iceland remains dynamic and the latest information from the Met Office shows that the situation today will continue to be variable.”

Gordon Brown said that airports were “taking advantage of the window of opportunity” as the impact of the volcano ash cloud temporarily lessened but he insisted passenger safety would remain “paramount”.

The Prime Minister said the effects from the Icelandic volcano were expected to strengthen again, but experts were looking at opening sections of airspace where it became available