Hundreds of European holiday makers on Bali were unable to return home Sunday along with six million others around the globe due to a volcanic eruption in Iceland.

The would-be travelers have been unable to fly home from Ngurah Rai Airport since Thursday because all European routes have been cancelled over fears planes could suffer catastrophic mechanical failures in contaminated skies over Europe.

Eyjafjallajokull volcano in Iceland erupted Wednesday sending tons of ash and debris into the atmosphere, with winds carrying the ash plume across Europe with airports in France, Germany, the Netherlands, Britain, northern Italy and more halting all flights due to the flight hazard formed by the volcano.

"I can't say exactly how many people are stranded, but it's in the hundreds," said Ngurah Rai Airport duty manager Mujhadi.

"We expect some to start flying to Paris tomorrow, but we will not be sure until more information comes through on the situation in Europe. England is still closed and could remain that way for some days."

Reuters reported that most experts and officials expected the cloud of ash would linger over Europe for several days.

Travel and tourism accounts for around 5 percent of global gross domestic product — some US$3 trillion — with Europe accounting for a third of that, much of it accruing over the summer months. Not all of this will be lost, but experts estimated a prolonged shutdown could cost up to $5-10 billion dollars a week in the industry.

But the impact will likely be wider. Most of the world's goods by volume may move by sea and land, but transport analysts estimate 40 percent by value moves by air. Through Sunday, a clampdown held across much of Europe, posing a growing problem for businesses — especially airlines, estimated to be losing $200 million a day — and for thousands of travelers stranded worldwide.

The European aviation agency Eurocontrol said only 4,000 flights were expected in European airspace on Sunday, compared with 24,000 normally. It said a total of 63,000 flights had been cancelled in European airspace since Thursday.

But as air travel across much of Europe was paralyzed for a fourth day on Sunday by a huge cloud of volcanic ash, Reuters reported that Dutch and German test flights carried out without apparent damage seemed to offer some hope of respite.

Dutch airline KLM said inspection of an airliner after a test flight showed no damage to engines or evidence of dangerous ash concentrations. Germany's Lufthansa also reported problem-free test flights, while Italian and French carriers announced they would fly empty airliners on Sunday.

The Association of Dutch Pilots (VNV) said that along with sister organizations it believed a partial resumption of flights, with some restrictions, was possible despite the continuing eruption from an Icelandic volcano.

"The concentration of ash particles in the atmosphere is in all likelihood so little it poses no threat to air transport," said VNV chairman Evert van Zwol.

German air traffic control slightly loosened its ban on flights from the country Sunday, allowing some traffic at Frankfurt and airports in the north. However, British Airways and Irish Aer Lingus highlighted uncertainty over any resumption of flights in the immediate future by canceling all of their flights for Monday.

The Jakarta Post, Jakarta