Much of the UK will remain a "no-fly" zone until at least 1am tomorrow, it was announced today.

Air traffic control company Nats said the situation involving the Icelandic volcanic eruption that has halted all but a handful of flights over the last few days "continued to be variable".

The latest Nats' decision, based on the latest Met Office information, means no flights will have been able to take off or land over most of England and Wales today.

But Nats did say planes could fly at 20,000ft over UK airspace, enabling airlines such as British Airways to fly aircraft in from abroad and land them at the northern England and Scottish airports that are operational tonight.

Nats said the situation was likely to change during the day and that it would make a further statement at around 9pm.

Travel advice

* Gatwick airport said that when flights did resume, anyone coming to the West Sussex airport more than four hours before their flight would be asked to leave.

* British nationals stranded overseas can ring the Foreign and Commonwealth Office advice line on +44 207 008 0000 or if they are in the USA or Canada they can contact 1-888-854-3574.

*Click here for volcano updates tagged #ashtag on Twitter

*The volcanohelp.eu site features updates and forums where people swap advice and assistance

A handful of flights were able to operate this morning from Newcastle and from Scottish airports. But Glasgow, having opened at 7am with a first flight taking off for Stornoway at 7.15am, had to shut again.

In travel advice on its website, the Foreign Office said today: "Given the likely numbers involved, it will take a matter of weeks before everyone can be repatriated."

Those Britons stranded in Europe were being advised to make their way to the French port of Calais, other Channel ports or a northern European port.

For those outside mainland Europe, the Government is working with the Spanish authorities to set up an "air hub" in Madrid.

Virgin Atlantic Airways said tonight it was "unable to operate any flights out of the UK until further notice".

The airline added that it was still working on plans to operate a small number of flights into the UK overnight.

Ryanair said it expected the ash crisis to impact its 2010/11 financial results by around six million euros (£5.26 million) a day.

Elsewhere, Royal Navy ship HMS Albion, which sailed to Santander in Spain, was coming home with around 280 stranded Britons on board as well as more than 450 troops.

Tonight, Ryanair said it had cancelled flights in northern Europe to 1pm on Thursday.

The budget carrier added it had also axed services between Ireland and the UK until 1pm on Friday so it could allow for extra flights from Ireland to continental Europe and from UK to continental Europe on Thursday.

Prime Minister Gordon Brown and Transport Secretary Lord Adonis stressed that the safety of passengers was paramount in the decisions about flights and that the Government was doing all it could to help to bring home the estimated 150,000 Britons stranded aboard.

Some airlines and tour operators arranged special flights to at least get stuck Britons back to mainland Europe.

Lord Adonis said that data from test flights continued to be assessed. Planemaking company Airbus and holiday airline Thomson were among those who have completed successful test flights.

A new £500 million vessel operated by Celebrity Cruises was due to set sail from from Southampton tonight to pick up holidaymakers from Bilbao in Spain.

The Port of Dover in Kent said it had handled more than 250,000 passengers since the ash crisis began - the equivalent of 600 Boeing 747 jumbo jets.

Eurostar continued to put on extra trains today on its London to Paris and Brussels routes and train companies - including Virgin Trains and the Government-run East Coast company - ran longer and extra trains.