It will not be safe for flights to take place across most of northern Europe tomorrow, UK Government ministers said tonight.
The announcement came after an 85-minute meeting of ministers at 10 Downing Street following another day when the Icelandic volcanic ash cloud prevented any flights in or out of the UK.
Ministers said everything was being done to try to help the thousands of Britons stranded abroad by the closure of UK airspace.
But with some clamouring for a relaxation of the restrictions, Transport Secretary Lord Adonis said that following advice from the Met Office it had been concluded that it would "not be safe for flights across most of northern Europe to take place tomorrow."
His comments, made in Downing Street as he was flanked by other ministers, came shortly after a British Airways Boeing 747 jumbo jet took off from Heathrow on a special test flight over part of the Atlantic.
This followed a number of other test flights across Europe by airlines anxious to get aviation moving again following four days of airport shutdowns which have stranded thousands of passengers.
Earlier, UK air traffic control company Nats had further extended the no-fly restriction over controlled UK airspace until 7am on Monday morning.
Security Minister Lord West, a former head of the Royal Navy, said the Government was looking at the option of possibly using the Royal Navy to try to bring people home.
Ministers also said Prime Minister Gordon Brown was speaking to his Spanish counterpart to see if Britons stranded in North America could be got home via Spain.
Business Secretary Lord Mandelson said Mr Brown had called a meeting of the "Cobra" civil contingencies committee tomorrow morning.
Lord Adonis said that a number of test flights had been carried out today and that data from these flights would be considered "during the course of tomorrow".
He added that European transport ministers would be meeting by video conference tomorrow.
Lord Mandelson said: "We will mobilise all possible means to get people home."
The BA test flight, with the airline's chief executive Willie Walsh aboard had left Heathrow shortly before 6pm and was expected to last two to three hours.
The plane, with a four-man crew, was flying up to height of 30,000ft.Reuse content