Air passengers are braced for further delays after warnings that a "new ash cloud" is spreading towards the UK as the volcano eruption in Iceland "strengthened".
Air traffic control company Nats described the situation as variable, but did say Scottish airports should be available from 7am and other airspace over England from 1pm, although not including the main London airports.
In an update shortly NATs said: "Since our last statement at 9pm yesterday, the volcano eruption in Iceland has strengthened and a new ash cloud is spreading south and east towards the UK.
"This demonstrates the dynamic and rapidly changing conditions in which we are working. Latest information from the Met Office shows that the situation is variable."
The Prime Minister has announced plans to use Royal Navy vessels to bring home some of the estimated 150,000 Britons stranded abroad.
A brand new £500-million cruise ship, the Celebrity Eclipse, is due to leave Southampton later for Bilbao to pick up around 2,000 British tourists from the northern Spanish port.
A meeting of emergency planning committee Cobra, chaired by Gordon Brown, was held on Monday night to discuss the latest updates on the ash cloud.
A Downing Street spokesman said the committee agreed the Government should "continue to do whatever it can" to return stranded Britons to the UK.
There has been pressure from airlines to restore flights, with carriers including British Airways pointing to the success of test flights to press home their arguments. BA said the flight ban had cost it around £15 million to £20 million a day.
