All non-emergency flights have been grounded in the UK from noon as ash from Iceland's volcanic eruption causes travel chaos.

The disruption, which also hit Irish and north European airspace, left thousands of travellers stranded at home and abroad.

National Air Traffic Services said all flights in UK airspace were grounded from noon to 6pm at the earliest.

A Nats spokesman said: "From midday until at least 6pm, there will be no flights permitted in UK controlled airspace other than emergency situations. This has been applied in accordance with international civil aviation policy. We continue to monitor the situation with the Met Office and work closely with airline customers and adjoining countries."

Hundreds of flights across the UK were already cancelled and airports in Scotland closed indefinitely. A Heathrow spokesman said: "We strongly advise passengers intending to fly from this time (12pm) not to travel to the airport. We will provide further updates as we get more information from air traffic control provider Nats."

Rochelle Turner, head of research for Which? Holiday magazine, said: "This is yet more bad news for air passengers in a year that has already seen much disruption to flights.

"Affected passengers are being offered a choice of a full refund or transfer on to another flight. But, airlines don't have to compensate passengers for loss of any additional elements to holidays, such as accommodation and car hire.

"It may be possible to claim for these additional elements on your travel insurance, but passengers will need to check their individual policies."

Hundreds of people were evacuated from their homes in south-west Iceland after a volcanic eruption yesterday at Eyjafjalljokull, which is part of the Mount Katla range. If volcanic ash particles are ingested into a jet engine, they accumulate and clog the engines with molten glass.

Forecasters believe the ash could take a number of days to disperse. Matt Dobson, a forecaster for MeteoGroup, the weather division of the Press Association, said: "The concern is that as well as the eruption, the jet stream passing through Iceland is passing in a south easterly direction, which will bring ash to the north of Scotland and Denmark and Norway. But it is impossible to say how much ash will come down."