All British airports will be closed from 12pm today as vast plumes of volcanic ash from Iceland forced the cancellation of thousands of flights.
In an unprecedented move which will leave hundreds of thousands of travellers stranded, British airspace will not reopen until at least 6pm local time, reports Daily Mail, London.
The disruption will have a devastating impact on families returning from the Easter holidays who were due to fly back to Britain this weekend.
All British airports will be closed from 12pm today as vast plumes of volcanic ash from Iceland forced the cancellation of thousands of flights.
In an unprecedented move which will leave hundreds of thousands of travellers stranded, British airspace will not reopen until at least 6pm.
The disruption will have a devastating impact on families returning from the Easter holidays who were due to fly back to Britain this weekend.
Matt Dobson, a forecaster for MeteoGroup, said ash would come down in Scotland, Denmark and Norway and could continue to affect airspace until Friday.
It cannot be seen from the ground as it blowing across Britain around three miles in the sky.
Ash can disrupt the engines of an aircraft and reduce visibility as well as affecting landing and navigation gear.
However, the substance does have one plus - for most people it will just mean a spectacular red sunset.
This morning a Heathrow Airport spokesman said 150 flights, both arrivals and departures, had been cancelled - at the busiest time of the day - and more flights were expected to be affected as the cloud of ash moved south.
The spokesman said all of the airport's domestic flights had been cancelled, as well as flights to and from Scandinavia and all U.S. arrivals that had not yet departed.
At Gatwick, 108 flights have been cancelled, while at least 17 flights are grounded at Stansted. Birmingham airport has seen 70 flights cancelled, while Bristol has halted around 20 flights.
Passengers are being advised to check with their airline before travelling to the airport.
The volcanic ash scare also caused Liberal Democrat Treasury spokesman Vince Cable to cancel planned General Election campaign visits to Dunfermline and Edinburgh today, the party said.
Thousands of passengers in Northern Ireland were also caught up in the air chaos, with the closure of Belfast International Airport and George Best Belfast City Airport.
Crowds who filled departures lounges for early morning flights to destinations throughout the UK were told services had been cancelled indefinitely.
Flight Sergeant Andy Carnell, a spokesman for RAF Search and Rescue, said that their aircraft would continue to fly.
He said: 'We will continue to provide full search and rescue cover, however we will consider all requests we get on a case by case basis
A spokesman for BAA Airports said this morning: 'Following advice from the Met Office, the National Air Traffic Service (NATS) has introduced restrictions to UK airspace this morning as a result of volcanic ash drifting across the UK from Iceland.
'Passengers intending to fly today are asked to contact their airline for further information and should expect disruption in the coming hours.'
Airlines also issued warnings of potential disruption.
A spokeswoman for easyJet said: 'Following the eruption of a volcano in Iceland earlier today, the Met Office have advised airlines that the ash plume may reach UK air space overnight.
'As a result this may cause significant disruption to flights departing the UK tomorrow.
'easyJet passengers are advised to check the website before they leave for the airport for any disruption information.'
The chaos comes after the volcano, which is under a glacier, erupted for the second time in less than a month - causing hundreds of people to flee the rising floodwaters.
Emergency workers rescued scores of tourists from around the Eyjafjallajokull glacier as it spewed smoke and steam. Around 800 residents had to be evacuated from their homes.
Rivers rose by up to ten feet (three metres) as the ferocious temperatures melted the glacier, turning it to water, which gushed down the mountainside.
Iceland's main coastal ring road was closed near the volcano, and workers smashed three holes in the highway in a bid to to give the rushing water a clear route to the coast and prevent bridges from being swept away.
Scientists said the eruption under the ice cap was ten to 20 times more powerful than the one last month, and carried a much greater risk of widespread flooding.
'This is a very much more violent eruption, because it's interacting with ice and water,' said Andy Russell, an expert in glacial flooding at the UK's University of Newcastle.
'It becomes much more explosive, instead of a nice lava flow oozing out of the ground.'
Civil protection official Agust Gunnar Gylfason said emergency workers rescued some 70 tourists and visitors trapped near the volcano since this morning. He said the party was now safe in a tourist facility and officials were trying to transport them out of the area.
No lives or properties were in immediate danger, Gylfason said and scientists added that there was no sign of increased activity at the much larger Katla volcano nearby.
Iceland's Meteorological Office said a plume of steam rose at least five miles (eight kilometers) into the air. Scientists aboard a coastguard plane that flew over the volcano said the new fissure appeared to be up to 1.2 miles (2 kilometres) long.
There were no immediate signs of large clouds of volcanic ash, which could disrupt air travel between Europe and North America. Some domestic flights were canceled, but Iceland's international airport remained open.
The volcano, about 75 miles (120 kilometres) east of Reykjavik, first erupted on March 20 after almost 200 years of silence, and petered out earlier this week.
But Gunnar Gudmundsson, a geophysicist at the Icelandic Meteorological Office, said there were a series of tremors overnight, and rivers in the area began rising Wednesday morning - strong evidence of a new eruption under the glacier.Last month's eruption struck near the glacier in an area that had no ice.
