FLIGHTS CANCELLED

And hundreds of flights from Heathrow, Gatwick, Stansted, Manchester, Luton and Birmingham have been cancelled.

British Airways has cancelled all domestic flights to all domestic airports.

An internal BA memo obtained by Sky News advises pilots: "The safety of our customers, crew and aircraft is of paramount importance and will not be compromised."

Officials said more airports could close completely as the ash drifts over the UK.

Airports are urging travellers to contact their airlines to check whether their journeys are affected.

Latest travel information - read how each of the airports is affected here.

More than 150 flights have been cancelled at Heathrow and 138 at Gatwick, including the majority of easyJet and Monarch departures.

Eighty flights have been cancelled at Birmingham.

A spokesman from National Air Traffic Services (NATS) said: "The Volcanic Ash Advisory Centre has issued a forecast that the ash cloud from the volcanic eruption in Iceland will track over Europe tonight.

"NATS is working with Eurocontrol and our colleagues in Europe's other air navigation service providers to take the appropriate action to ensure safety in accordance with international aviation policy."

NATS has the authority to close airpsace around airports - which it has so far done in Scotland - and will consider other airports as the day goes on.

Manchester Airport said flights would be cancelled and delayed between 7am and 1pm.

Some easyJet flights due to depart from Stansted Airport have also been cancelled.

Sky's Enda Brady, reporting from Heathrow, said things were only expected to get worse throughout the day.

"I've been told that there won't be any good news coming out of the airport today."

Brady said that arrivals from the USA were particularly badly affected due to the flight path.

Liberal Democrat Shadow Chancellor Vince Cable cancelled campaign visits to Dunfermline and Edinburgh due to the Scottish airport closures.

Passengers told Sky about massive disruptions to their plans.

One said: "I'm due to get married in Essex tomorrow and my family were flying in from Belfast. That's not going to happen now."

Another said he had been sent home from Manchester airport and told to ring Monarch for more information but it was impossible to get through.

The volcanic eruption was the second in Iceland in less than a month.

The heat from it is so fierce it melted part of the Eyjafjallajokull glacier, sparking huge floods.

Weather experts also said the ash could take a number of days to disperse.

Dr Matthew Roberts, from the Iceland Meteorological Office, told Sky News he believed that there were unlikely to be any more explosions.

He said that the fine ash particles being blown across Europe should only "pose minimal health hazards" to people in the UK.

The volcanic ash jams machinery on planes and there have been many instances of damage to jet aircraft in the past.

After the Galunggung volcanic event in 1982, a British Airways Boeing 747 flew through an ash cloud that fouled all 4 engines, stopping them.

The plane descended from 36,000 feet (11,000m) to 12,000 feet (3,700m) before the crew could manage to restart the engines.

Sky weather presenter Lucy Verasamy said: "The ash cloud from Iceland represents a risk to aircraft since it can damage engines.

"But in this instance it won't affect the weather - although massive and prolonged eruptions can cause a cooling of the climate."