Ash clouds caused by a surge in activity from Iceland's Eyjafjoell volcano brought fresh travel chaos to thousands of passengers Monday, as airports shut in London, Ireland and the Netherlands.

London Heathrow, Europe's busiest air hub, and London Gatwick, were hit with a new round of delays and cancellations, as other airports inside the no-fly zone stayed shut until at least 1200 GMT.

Amsterdam, one of Europe's key air interchanges, and Rotterdam airports in the Netherlands were both closed from 0400 GMT to 1200 GMT as the ash cloud moved east.

Around 1,000 flights in Europe would be cancelled, said the intergovernmental agency coordinating air traffic control, Eurocontrol.

Heathrow and Gatwick reopened at 0600 GMT after a six-hour shutdown, but all airports in Northern Ireland and the Isle of Man, Scotland's busiest airport, Edinburgh, plus Aberdeen and Inverness stayed shut until at least 1200 GMT.

Meanwhile, Wales's main airport Cardiff was closed, as was Swansea.

In England, Bristol in the southwest was also shut. London's other main airports City, Luton and Stansted were open but advising passengers to check with their airlines for fresh updates.

The National Air Traffic Services, which manages British airspace, said: "The volcanic ash cloud continues to change shape and two key areas affect operations stretching from the south of England to Northern Ireland, and over much of mainland Scotland to the Shetland Isles."

Eurocontrol said it expected a lower than usual 28,000 flights in Europe Monday.

"This is approximately 1,000 less than on a normal day, and is due to the expected impact of the current closure of airspace in the south-east of the UK and in the Netherlands," it said in a statement.

On Sunday, Eurocontrol said, disruptions in Ireland and the northwest of Britain resulted in a loss of some 400 flights.

The latest ash closures came at the beginning of a week where air travel disruption was already expected due to a five-day strike by British Airways cabin crew set to kick off Tuesday.

Europe's skies were partially closed for up to a week in April following the eruption of Iceland's Eyjafjoell volcano, in the biggest shutdown of the continent's airspace for more than 50 years.

In Ireland, Dublin airport was to reopen at 1100 GMT after a 17-hour shut-down as the cloud moved east.

Sligo airport was to reopen at 1300 GMT, with Donegal to follow at 1300 GMT.

The volcanic dust at more concentrated levels presents a danger to plane engines, though some industry officials have complained that the safety measures and airport closures have been excessive.

The international airline industry body, IATA, has estimated last month's shutdown cost carriers some 1.7 billion dollars (1.4 billion euros, 0.7 billion pounds).

earlier related report
London airports close in new ash shutdowns: air authority
London (AFP) May 17, 2010 - London's two main airports closed early Monday as a new ash cloud from the Iceland volcano drifted south, aviation authorities said, threatening fresh travel chaos for thousands of passengers.

Heathrow -- Europe's busiest air hub -- and Gatwick airports shut at 1:00 am (0000 GMT) for at least six hours after stronger eruptions from the volcano, which last month paralysed Europe's skies.

"The high density ash cloud continues to move further south in the early hours" of Monday, said a statement from the National Air Traffic Services (NATS), which manages British airspace.

The new closures would be imposed from 1:00 am (0000 GMT) until 7:00 am (0600 GMT), said the air traffic controllers.

Dublin and several other Irish airports, as well as all airports in Northern Ireland, remained shut early Monday. But others in northern and central England were set to reopen.

In the Netherlands meanwhile, the authorities announced the closure of the airports in Amsterdam and Rotterdam from 6:00 am (0400 GMT) to 2:00 pm Monday.

The latest ash closures came at the beginning of a week where air travel disruption was already expected due to a five-day strike by British Airways cabin crew set to kick off Tuesday.

Europe's skies were partially closed for up to a week in April following the eruption of Iceland's Eyjafjoell volcano, in the biggest shutdown of the continent's airspace for more than 50 years.

Experts fear the volcanic ash can damage jet engines and create a serious risk of a crash.

"There is slightly increased activity for the past two days, there has been some ash fall around the glacier," Bjoern Oddsson a University of Iceland vulcanologist told AFP.

"The column (of smoke) has increased and rises up to eight kilometres (five miles)," as opposed to six kilometres in previous days.

But its effect on European flights depended entirely on the winds, he added.

Britain's NATS also ordered the closure of several smaller airports around London and southeast England early Monday.

But they allowed restrictions to be lifted in northern and central England, from 0000 GMT after the ash cloud drifted south and away from their airspace.

That allowed Manchester Airport in northwest England, Britain's busiest outside London and among the 20 busiest in Europe, to reopen after several hours' closure Sunday. Birmingham, Liverpool, and Leeds-Bradford also reopened.

In Scotland, as Prestwick prepared to reopen Aberdeen Airport, further northeast, was set to close. Airports in the Western Isles and along Scotland's west coast remained shut.

Earlier, aviation regulators in the Republic of Ireland extended a closure of Dublin airport by three hours to at least 1100 GMT Monday. The airport closed at 1800 GMT Sunday.

The other two main airports, Cork and Shannon, remain open until further notice, the Irish Aviation Authority (IAA) said.

Of the smaller hubs, Donegal was to remain closed until at least 1100 GMT, while Ireland West (Knock) and Sligo were to reopen at 0800 GMT.

Kerry is open until further notice, while Galway and Waterford would reopen at 0500 GMT Monday.

North Atlantic flights crossing Irish airspace would not be affected, said the IAA.

The latest shutdowns drew renewed attacks from the aviation industry, which has been hard hit by the ash cloud chaos.

The international airline industry body, IATA, has estimated last month's shutdown cost carriers some 1.7 billion dollars (1.4 billion euros, 0.7 billion pounds).

Virgin Atlantic boss Richard Branson branded Sunday's closure of Manchester Airport as "beyond a joke".

"We need strong leadership to intervene to avoid doing further unnecessary damage to the UK economy and lives of travellers," he said.

Eurostar, which runs high-speed rail services linking London with Paris and Brussels via the Channel Tunnel, said it was laying on extra trains between the British and French capitals Monday to answer an expected surge in demand.